What is Mon Mod?

Mon Mod (Monster Modifier) is a web-based tool for creating, modifying, and scaling D&D 5th Edition monster stat blocks. Need to tweak a creature for tonight's encounter, build one from scratch, or bump something up to a different Challenge Rating? The tool handles the math and formatting for you.

Quick start

Three ways to get going:

• Create a blank monster: Hit Create New in the toolbar, pick Blank Monster, and fill in the fields. The tool generates balanced stats from the CR and role you choose.
• Generate a random monster: Click Create New and pick Random Monster. You can optionally lock in a creature type, role, and CR before generating a fully built creature in one click.
• Import an existing monster: Use Search to find something in the Open5e database, or use Import to bring in a stat block from JSON, Markdown, an image (OCR), or a PDF.

The two-panel layout

The interface splits into two areas:

• Editor (left panel): Tabbed controls for configuring the monster's identity, abilities, adjustments, and more.
• Preview (right panel): A live stat block that updates as you make changes. You can also click values in the preview to edit them inline.

Mobile and tablet support

The tool works on phones and tablets. On small screens, tab buttons collapse into a dropdown, and the editor/preview panels use a fluid 45%/55% split instead of fixed widths. Identity fields reflow at narrow widths too. See the Mobile section for touch-specific features like help toasts.

The dark header bar across the top has a few controls worth knowing about:

• Documentation link: Opens this page.
• Theme button: Switches between visual themes for the stat block (parchment, dark, etc.).
• Sign In / Account menu: Create an account or log in for cloud features. Once signed in, the menu includes Send a Note for sending feedback directly to the developer.
• Support button (heart icon): Opens the Ko-fi page if you want to support the project.

What signing in enables

Everything works locally without an account. Signing in adds:

• Cloud save: Monsters are saved to the cloud, not just your browser's local storage.
• My Monsters: A library of up to 10 saved monsters (100 for supporters), accessible from any device.
• My Abilities: Save up to 10 ability templates (100 for supporters) and reuse them across monsters.
• My Spells: Save up to 10 spell templates (100 for supporters) for quick access.
• My Fields: Save up to 10 custom fields (100 for supporters): creature types, damage types, conditions, languages, skills, and senses that persist across sessions.
• Account modal: Manage your profile, avatar, linked accounts, supporter status, and data from one central panel.
• My Themes (supporter-only): Build and apply custom color themes for the stat block.
• Supporter badge: A gold ring around your avatar.
• Synced settings: Theme preferences sync to the cloud. Display settings like format and background stay local.

The toolbar sits below the header. It is where the most common actions live.

Create New

Opens a panel over the editor with two options. No confirmation dialog; the current monster is replaced immediately.

Options:

• Blank Monster: Starts with an empty stat block. Pick a CR and the tool generates baseline stats using the current type and size from the Identity tab. Role is not available for blanks.
• Random Monster: Generates a complete creature with randomized stats. You can narrow things down with a few options:
  • Type: Lock to a specific creature type (Fiend, Undead, etc.) or leave it random.
  • Size: Pick a size or let it be chosen for you.
  • Role: Set a combat role (Brute, Controller, etc.) or randomize. Sub-Role is always random and cannot be set in this dialog.
  • CR variance: How far from the target CR the result can land. Good for generating something "roughly CR 5."
  • Strict type matching: Only assigns abilities and traits that make thematic sense for the creature type.

Search

Opens a modal for searching the Open5e monster database (SRD plus community content). Saved monsters also show up here if you are signed in. Type part of a name, pick a result, and it loads into the editor. Close the modal with the X button, Escape, or by clicking the overlay.

Results are deduplicated by default, keeping the preferred source (SRD/WotC first). Uncheck De-dupe next to the Filters button to see every version from every source.

Import

Brings in a stat block from an outside source. Supported formats:

• JSON: Paste Open5e-format JSON directly.
• Markdown: Paste a Markdown-formatted stat block (e.g., from Homebrewery or GM Binder).
• Image / OCR: Upload a photo or screenshot of a stat block. You get an interactive crop modal where you draw a box around the stat block, then the tool runs OCR to extract and convert the text.
• PDF: Upload a PDF containing a stat block.

OCR works best with clean, high-contrast images. A cropped screenshot of a single stat block gives much better results than a photo of a full page.

When an import fails, an anonymous error report is sent automatically to help diagnose issues. See Privacy & Telemetry for details.

Help Box

Hover over (or focus) any control in the editor to see a short explanation in the help box. Particularly useful for unfamiliar options like scaling modes or CR variance.

Five tabs, each grouping related settings so you can focus on one aspect at a time.

4a. Identity Tab

This is where you define who and what the monster is: name, type, size, scores, and all the small details that fill the top of a stat block.

Basic Info

• Name: The creature's display name.
• Challenge Rating (CR): A stepper that sets difficulty. Supported values: 0, 1/8, 1/4, 1/2, and 1-30. Higher CR means more HP, better attack bonuses, and so on.
• Initiative tiers: How the monster's initiative is determined, following the 2024 Monster Manual convention. Cycles through three states: None (no bonus), Proficiency (adds proficiency bonus), and Expertise (double proficiency bonus).

Type, Subtype, Size, Alignment

Standard dropdowns with all official options, plus the ability to type in custom entries. If your monster is a "Symbiotic Ooze" or "Chaotic Adorable," go for it. The alignment dropdown includes all 9 "Typically X" variants from the 2024 Monster Manual format, standard alignments, and "Any X" options.

Subtype: Text field for the parenthetical in the meta line (e.g., "humanoid (any race)" or "fiend (demon)"). Leave it blank to skip the parentheses.

Habitat: Free-text field for the creature's typical environment (Forest, Underdark, Arctic, etc.). Included in exports.

Role & Sub-Role

Roles shape how stats are distributed when creating from scratch. A Brute gets more HP and melee damage; a Skirmisher favors speed and Dexterity. Sub-roles add a secondary emphasis. These are purely for generation and do not appear in the final stat block.

Spellcasting Ability

Which ability score governs the monster's spellcasting (Wisdom, Charisma, Intelligence, etc.). Affects spell save DC and spell attack bonus.

Ability Scores

The six classic scores (STR, DEX, CON, INT, WIS, CHA). When you create a new monster, these are auto-generated from the CR and role as a balanced starting point. Edit any of them freely afterward.

Speed

Five movement types: Walk, Fly, Swim, Climb, and Burrow. Set any you do not need to 0 or leave blank.

Senses

Multi-select with range steppers for each sense (Darkvision, Blindsight, Tremorsense, Truesight). You can add custom entries too. Passive Perception is calculated automatically from Wisdom and proficiency.

Languages

Multi-select with all standard D&D languages, plus two special toggles:

• "No languages": The creature has no languages (typical for beasts and some monstrosities).
• "Can't speak": It understands languages but cannot speak. Adds "understands X but can't speak" to the stat block.

Telepathy is available as a language option with a configurable range (default 120 ft.). Custom entries are supported for homebrew settings.

Save & Skill Proficiencies

Toggle saving throw and skill proficiencies. Bonuses are calculated automatically from ability scores and proficiency bonus (set by CR).

Damage Vulnerabilities, Resistances, Immunities & Condition Immunities

Multi-select lists for all four categories. Custom entries are supported through My Fields. The damage lists include grouped physical options ("Bludgeoning, Piercing, and Slashing" with nonmagical, non-silvered, and non-adamantine variants) alongside the individual types. Vulnerabilities appear before resistances in the stat block.

Notable Loot

Free-text field for treasure or items the creature carries. Shows at the bottom of the stat block, handy if you want loot info right there during play.

4b. Abilities Tab

Where you build the monster's actions, traits, reactions, and special abilities. This is the stuff that matters in combat.

Adding abilities

Click Add Ability in the Abilities toolbar to create a blank one. It starts as freeform text; set its type to change what fields are available.

There is also a Use Template button that opens the Browse Abilities modal and adds a new ability pre-filled from whatever template you pick. This always creates a new ability; it will not overwrite anything.

Browse Abilities

Click Use Template (or the Browse Abilities shortcut) to open a modal for finding and applying pre-built abilities. The modal has tabs for Traits, Actions, Bonus Actions, Reactions, Legendary, and Spells. Each tab has sub-headers for browsing within that category.

• Feature catalog entries: Entries that affect CR show an "Affects CR" badge. Applying one links it to the CR system, so its contribution shows up in the CR diagnostic.
• CR-linked editing: After applying a catalog feature, you can edit the text freely without breaking the CR link. The mechanical values stay connected even if you tweak the description.
• Search: A search bar filters results within the active tab.
• My Abilities: Your saved custom templates (requires sign-in) appear in the relevant tabs.
• Spell templates: The Spells tab searches the Open5e spell database. My Spells (requires sign-in) show up here too.

Ability types

• Attack: Melee or ranged weapon attacks, or spell attacks. Generates the standard "to hit" line with damage.
• Save: Abilities that force a saving throw (area effects or single-target).
• Spell: A named spell with level, frequency, shorthand display, and optional save info. Frequency options: At Will, 3/Day, 2/Day, and 1/Day. Slot-based casting is controlled by the display format (2014 Slot Caster), not per-spell frequency.
• Freeform: Plain text with no mechanical fields. Use for traits, lore, or anything that does not fit the other types.

Section

The Section dropdown controls where the ability lands in the stat block. Changing it moves the ability to that section. Options: Traits, Actions, Bonus Actions, Reactions, Legendary Actions, Mythic Actions, and Lair Actions.

Usage / Recharge

Sets how often the ability can be used: At Will, Recharge 5-6, Recharge 6, X/Day, X/Short Rest, or X/Long Rest. The X/Day variants show a count input for number of uses. Hidden for spells, which use the Frequency field instead.

Attack configuration

When set to Attack type, you configure:

• Attack type: Melee Weapon, Ranged Weapon, Melee or Ranged Weapon, Melee Spell, or Ranged Spell.
• Reach / Range: How far it extends (5 ft. reach, 120 ft. range, etc.).
• Targets: How many targets it can hit.
• Notes: Free-text for extra detail like "with disadvantage" or "against a grappled target." By default the note goes after the to-hit line. Check After targets to place it after the target description instead.

Save configuration

When set to Save type:

• Saving throw ability: Which score the target rolls against (DEX, CON, WIS, etc.).
• Effect: What happens on a failure.
• Area shape and size: If the ability covers an area.

Area options

Several area shapes, each with relevant sub-fields:

• Target(s): One or more specific targets. Configure count and range.
• Radius (from self): An emanation centered on the creature.
• Cone: Cone originating from the creature.
• Line: Straight line from the creature.
• Sphere: Spherical area at a point within range.
• Cube: Cubic area at a point within range.
• Cylinder: Cylindrical area at a point within range.

Special checkboxes

• Must be visible: Adds "that [monster name] can see" to the targeting text. Good for gaze attacks and the like.
• Exclude self: For area effects. Keeps the monster from being hit by its own ability.

Damage entries

Each ability can have one or more damage entries. For each one you set:

• Dice / flat amount: The damage dice (e.g., 2d6) or a flat number.
• Damage type: Slashing, Fire, Necrotic, Healing (for abilities that restore HP), etc.
• Ability modifier: Whether to add an ability modifier to the damage.
• "Scales with CR" checkbox: When checked, this damage automatically adjusts when you change the monster's CR. See Scaling & CR for details.

Riders

Riders are extra effects that trigger on a hit or failed save. Each one is organized into five rows:

• Effect row: The condition applied (Grappled, Poisoned, Restrained, etc.), with a duration field and an optional "Affects" qualifier.
• Save row: A saving throw to resist or end the condition, with save ability (STR, CON, DEX, etc.) and a "Half on save" checkbox. For save-to-end riders, a timing option lets you pick start or end of the target's turn.
• Damage row: Extra dice damage tied to the rider, with a damage type and an optional "Scales with CR" checkbox. When checked, rider damage scales alongside the monster's CR just like primary damage.
• Movement row: Forced movement (Push, Pull, Teleport, or Free Move), each with a distance field. Free Move also has a "No opportunity attacks" checkbox.
• Extra row: Freeform text for anything that does not fit the other rows, plus a remove button.

Description preview

As you configure an ability, the stat block text is generated in real time. If the wording is not quite right, you can edit the description directly with a text override. A reset button brings back the auto-generated version. (For freeform abilities there is nothing to generate, so the reset button does not appear.)

Saving abilities for reuse

Click the save icon on any ability to store it in My Abilities or My Spells (depending on type). Saved abilities can be loaded into any future monster from the template picker.

Managing abilities

• Duplicate: Copies the ability. Good for making a stronger or weaker variant.
• Delete: Removes it. Takes three clicks as a safety measure.
• Enable / Disable: Temporarily hides an ability from the stat block without deleting it.
• Drag to reorder: Grab the drag handle to rearrange abilities in the list.
• Change section: Use the Section dropdown to move an ability between Traits, Actions, Bonus Actions, Reactions, Legendary Actions, Mythic Actions, or Lair Actions.

Special features

• Multiattack: Configure a Multiattack action combining multiple attacks. The tool generates standard Multiattack text based on the attacks you include.
• Legendary Actions: Enable legendary actions and set the per-round budget. Individual abilities go into the Legendary Actions section via the Section dropdown.
• Legendary Resistance: The classic "X/Day" feature.
• Mythic: Enable mythic traits and actions for two-phase boss fights.
• Lair: Add lair actions and regional effects.

Unified Ability Catalog

The Browse Abilities modal includes a built-in catalog of 129 feature entries, all browsable through the tabbed interface. These go beyond simple text templates; they are mechanically complete abilities, including things like:

• Charge attacks: Bonus damage or knockdown when the creature moves before attacking.
• Trigger-based abilities: Reactions and traits that fire on specific triggers: on-death explosions, retaliatory strikes, that sort of thing.
• Weapon attacks with riders: Attacks with built-in grapple, restrain, or other conditions, with escape DCs already configured.

Entries that affect CR are marked with an "Affects CR" badge. Applying one links it to the CR system automatically, so its damage, save DC, and conditions are factored into the CR diagnostic without extra setup.

4c. Adjustments Tab

Fine-tune a monster's stats without editing individual fields. Useful when you want to make something tougher or weaker without rebuilding it.

Flat stat adjustments

Add or subtract flat amounts from:

• Hit Points (HP)
• Armor Class (AC)
• Attack bonus (ATK)
• Save DC
• Spell DC
• Speeds (all movement types)

Ability score adjustments

Add or subtract from individual scores (STR, DEX, CON, INT, WIS, CHA). Downstream values like save bonuses and skill checks update automatically.

Ratio adjustments

• HP ratio: Multiply HP by a percentage. Want a creature 50% tougher? Set it to 1.5x. Glass cannon? Try 0.5x.
• DPR ratio: Multiply damage per round by a percentage. Affects all damage entries marked "Scales with CR."

CR settings

• Target CR: The CR you want to hit.
• Benchmark edition: Use 2024 or 2014 stat benchmarks. The two editions have different expectations for HP, AC, and damage at each CR.
• CR variance: How strictly stats must match the target. A loose variance lets the monster deviate without the tool flagging it.

CR Diagnostic

A breakdown of how the tool calculates CR, showing:

• Defensive CR (based on HP and AC)
• Offensive CR (based on DPR and attack bonus / save DC)
• Final CR as the average of the two

Check the diagnostic after big changes. It will tell you whether your monster is over- or under-tuned for its CR.

4d. Source Tab

Shows up for imported monsters. Gives you low-level control over the raw data.

• JSON editor: Paste or edit the raw JSON that defines the monster.
• Load Monster button: Parses the JSON and loads it into the editor.
• Source Edition: Whether the original stat block was 2024 or 2014.
• Output Edition: Which edition's benchmarks to scale toward. Located next to Source Edition in Import Settings, this is separate from Display Format (which only affects appearance). Use it to convert between editions; for example, import a 2014 monster and scale its stats to 2024 benchmarks while keeping whatever display format you prefer.
• Scaling Mode:
  • Input: Preserves the original stat ratios and scales proportionally.
  • Benchmark: Fits stats to the standard benchmark values for the target CR.
• Source CR override: If the tool detected the wrong CR from import, correct it here.

Imported Bonuses

When you import a monster, the tool compares each skill bonus, save bonus, and initiative bonus against standard calculation (ability modifier + proficiency bonus). If a value is different, the tool records the difference as a delta and displays it here.

For example: an imported monster has Perception +10, but standard calculation gives +1 (WIS -1, plus PB +2). The tool records a delta of +9. This delta is preserved when you scale to a different CR; the standard part adjusts naturally, and the +9 carries forward.

• Input scaling mode: Deltas are applied. Bonuses match the imported values at the original CR and scale proportionally when CR changes.
• Benchmark scaling mode: Deltas are ignored; everything uses pure standard calculation. Switching back to Input re-applies them.

Each delta row has an editable value and a remove button. You can:

• Edit a delta to fix import errors (e.g., a typo in the stat block).
• Remove a delta to drop an individual custom bonus.
• Add a new delta via the "Add bonus..." dropdown to manually assign a custom bonus to any skill, save, or initiative.
• Clear All to wipe every delta and revert to standard calculation.

Changed values flash in the preview when you edit deltas, same as any other modification.

4e. Compare Tab

View two stat blocks side by side. Handy for checking that you didn't accidentally break something, or for comparing your custom monster against an official one.

• Capture: Snapshots the current stat block so you can keep editing and see what changed.
• Search Monsters: Opens a modal to find and load a different monster for comparison. Works like the toolbar Search; dismiss with X, Escape, or clicking the overlay.
• Edit / Copy / Clear: Modify the snapshot, copy it, or clear it.
• Zoom: When a compare monster is loaded, zoom controls appear. Click the percentage label to reset to fit-to-width.

The right side of the screen shows a live stat block that updates as you work. It is not just a preview; you can edit directly in it.

Interactive editing

Click most values in the stat block to edit them inline:

• Click the AC value to open a popover with both the number and a Source field for the armor description (e.g., "natural armor," "breastplate"). Leave Source blank to skip the parenthetical.
• Click the initiative value to set the proficiency tier: None, Proficiency, or Expertise.
• Click Size, Type, or Alignment in the meta line to edit that field. The Type popover also has a Subtype input.
• Click HP to adjust hit points or the hit dice formula.
• Click damage values in abilities to change dice or amounts.
• Click save DCs to adjust difficulty.
• Click conditions and other text to edit them.
• Click an individual skill bonus for a popover with a Remove button.
• Click an individual sense for a popover with a range input and Remove button.
• Click an individual language for a Remove popover.
• Click the Skills, Senses, or Languages label to jump to the Identity tab.

Drag abilities

Grab an ability's name in the stat block to drag it to a new position within its section.

Hover controls

Hovering over sections reveals extra controls:

• × button: Remove an ability.
• + button: Add a new ability to that section.

Resize handle

A drag handle on the right edge lets you resize the stat block's render width. Default is 800px. You can also use the +/- buttons in sheet controls.

Zoom-to-fit scaling

The stat block always renders at its full intended width. When the preview area is narrower, it scales down to fit without horizontal scrolling. Use the Zoom controls to adjust, and click the percentage to reset to fit-to-width. Exports (PNG/PDF) always capture at full render width, not the zoomed size.

Sheet controls

Above the stat block you will find:

• Sheet Theme: Change the stat block's visual appearance.
• Format: Switch between 2024 and 2014 stat block layouts.
• Image: Two controls: a checkbox to show/hide the creature image, and an upload button. When visible, drag the image to reposition it above, beside, or below the AC/HP/Speed block. Corner handles resize, center handle pans. On touch devices, tap to reveal handles.
• Background: Three options: Texture (parchment), Solid (flat color with a picker), or Transparent.
• Single-Column: Forces a single-column layout. Useful for narrow displays or export.
• Notes: Add DM notes below the stat block.
• Width: Stat block render width in pixels (default 800). Use +/- or type a value.
• Zoom: Zoom in or out. Click the percentage to reset to fit-to-width.

On mobile, these are hidden behind a Settings button. Tap to expand.

Export options

Export your stat block in several formats:

• JSON: Open5e format, 5eTools Homebrew format, or Improved Initiative format.
• Markdown: Standard or Homebrewery Markdown, for VTTs, note-taking apps, and similar.
• XML: Fight Club 5e format.
• Image: PNG or PDF. Good for printing or sharing.

Mythic actions are included in all export formats. When Notes are enabled in Sheet Controls, DM notes are included in JSON, Markdown, and XML exports.

A free account unlocks cloud storage and sync. Without one, everything lives in your browser's local storage and will vanish if you clear your browser data.

My Monsters

Save up to 10 monsters to the cloud (100 with supporter status), accessible from any device. Your most recent monsters are also cached locally for quick access. You can export multiple saved monsters as a single JSON file for backup or sharing, and import from a JSON file into your library.

My Abilities

Save ability templates (attacks, traits, reactions) for reuse across monsters. Free accounts get 10 slots, supporters get 100. Built the perfect Breath Weapon or a custom trait you use on all your homebrew dragons? Save it once and load it into anything.

My Spells

Save spell templates for reuse. 10 slots free, 100 for supporters. Useful for custom or modified spells not in the Open5e database.

My Fields

Extend the built-in lists with your own entries. 10 slots free, 100 for supporters.

• Custom creature types
• Custom damage types (e.g., "Psychic Fire" or "Void")
• Custom conditions
• Custom languages
• Custom skills
• Custom senses

They show up in the relevant dropdowns and multi-selects throughout the editor, just like the built-in options.

Send a Note

In the account menu when signed in. Send feedback, bug reports, or feature suggestions directly to the developer. Messages are private and do not need an external email client.

Account Modal

Central hub for managing your profile and data:

• Profile: Set your display name and avatar. Upload a custom image or pick from a library of creature icons.
• Linked accounts: View and manage sign-in providers.
• Supporter status: Check your benefits and donation history.
• Storage usage: How many monsters, abilities, spells, and fields you have saved vs. your limits.
• Data export/import: Back up everything, or restore from a previous backup.
• Privacy: Opt in to enhanced telemetry (browser info and user-created text included in error reports). Off by default. See Privacy & Telemetry.
• Clear data: Remove all saved content while keeping the account.
• Delete account: Permanently delete your account and all associated data.

Supporter Benefits

Monster Modifier is free. Donations through Ko-fi help keep development going. Each $1 grants one month of supporter status; recurring donations keep it active continuously.

Supporter benefits:

• No ads (non-supporters see a sticky banner on mobile and an in-panel ad on desktop)
• Increased storage: 100 monsters, 100 abilities, 100 spells, 100 custom fields (up from 10 each)
• Access to My Themes for custom color themes
• A gold supporter badge around your avatar
• Feelings of joy and satisfaction

My Themes

Supporter-only. Build your own color theme for the stat block by choosing colors for backgrounds, text, borders, accents, and other elements. Custom themes show up alongside the built-in options in the theme picker and sync to your account.

How it works

Every change you make is snapshotted automatically. Experiment freely; every previous state is recoverable.

Keyboard shortcuts

• Ctrl+Z (or Cmd+Z on Mac): Undo the last change.
• Ctrl+Shift+Z (or Cmd+Shift+Z): Redo.

Coalescing

Rapid changes (typing a name letter by letter, clicking a stepper repeatedly) get grouped into a single undo step. Pressing undo will not step back one character at a time; it jumps to the state before you started typing.

How CR calculation works

Challenge Rating is the average of two components:

• Defensive CR: Based on Hit Points and Armor Class. More HP and higher AC push it up.
• Offensive CR: Based on Damage Per Round (DPR) and attack bonus or save DC. More damage and better accuracy push it up.

The final CR is the average of those two. This follows the DMG guidelines.

Benchmark editions

The 2024 and 2014 DMGs have different benchmark tables for what stats a monster should have at each CR. The 2024 benchmarks generally expect higher HP at high CRs, for instance.

Pick the edition that matches the monsters you are running. If you use the 2024 Monster Manual as your baseline, go with 2024 benchmarks.

Scaling modes

• Benchmark mode: Fits stats to the standard benchmarks for the target CR. A CR 5 monster scaled to CR 10 gets the HP, AC, damage, and attack bonus the benchmark table expects at CR 10.
• Input mode: Preserves the original stat ratios and scales proportionally. If the original had unusually high HP but low AC for its CR, the scaled version keeps that same ratio. Good for maintaining a monster's character while adjusting power level. Also preserves imported bonus deltas for skills, saves, and initiative.

How "Scales with CR" works

Check "Scales with CR" on a damage entry and it will adjust automatically when the target CR changes. The tool recalculates dice to match the expected DPR for the new CR, spreading damage across all scaling entries proportionally.

Entries without the checkbox are fixed; they stay the same regardless of CR changes.

Mark your primary attacks as "Scales with CR" and leave situational or low-impact damage fixed. Rider damage can also scale when its own checkbox is checked.

Cross-edition conversion

The Output Edition setting in the Source tab lets you convert between 2014 and 2024 rules. Set Source Edition to match the original stat block, then set Output Edition to the target. Stats scale toward the output edition's benchmarks while keeping the creature's relative strengths and weaknesses. This is separate from Display Format, which only changes the visual layout.

Source CR vs Target CR

Source CR is what the monster was originally designed for (detected from import or set manually). Target CR is where you want it. The gap between the two drives how much stats are adjusted during scaling.

Three stat block format options, matching how D&D 5th Edition presentation has evolved:

2024 Format

The current Monster Manual style from the 2024 revision. Spells are listed inline as individual actions or traits with frequency tags (e.g., "3/Day: Fireball"). Each spell is self-contained, which makes it faster to run at the table.

2014 Slot Caster

The classic PHB spellcasting format. Spells grouped by level with slot counts (e.g., "1st level (4 slots): shield, magic missile"). This is the traditional format from the original 2014 Monster Manual, with monsters casting spells the same way PCs do.

2014 Innate Caster

Innate spellcasting from the 2014 rules. Spells grouped by frequency (At will, 3/day each, 1/day each) without spell slots. For creatures with natural magical abilities rather than learned casting.

How format affects spell display

Switching formats changes how the same spells are presented. The spells themselves do not change, only the formatting. You can convert a 2014-style monster to 2024 presentation (or back) with a single click.

Shortcut	Action
Ctrl+Z / Cmd+Z	Undo
Ctrl+Shift+Z / Cmd+Shift+Z	Redo
Ctrl+Y	Redo (alternative)
Escape	Close modals, popovers, and overlays
↑ ↓ in CR inputs	Increment / decrement CR value

Start with a template, then customize

Don't build every ability from scratch. Search Open5e for a similar monster and modify it. You get a solid baseline and save time on common stuff like Multiattack, bite attacks, and breath weapons.

Use roles for balanced stat generation

When creating a new monster, set a role (Brute, Skirmisher, Controller, etc.). Roles distribute scores and stats to create a distinct combat identity. A Brute with high STR and CON plays differently from a Controller with high INT and WIS, even at the same CR.

Check the CR Diagnostic after making changes

The CR Diagnostic in the Adjustments tab shows exactly how your monster's CR is being calculated. After adding abilities or tweaking stats, glance at it to make sure you are landing where you intend. If offensive CR is way above defensive CR, you have a glass cannon: dangerous but fragile.

Use "Scales with CR" on damage you want to auto-adjust

Planning to rescale the monster later? Mark the main damage sources (primary attacks, breath weapons, etc.) with "Scales with CR." Leave minor or thematic damage (poison riders, environmental effects) fixed. Keeps scaling clean.

Save custom abilities and spells for reuse

Homebrewed a signature ability (a custom breath weapon, a unique reaction)? Save it to My Abilities. Next time you build a monster, it is one click away instead of a rebuild from memory.

Use Compare to verify changes against the original

Before committing to your modifications, capture the original stat block in the Compare tab. Then make your changes and compare side by side. Especially useful when scaling to a new CR, so you can see exactly what shifted.

Responsive layout

The editor and preview use a fluid 45%/55% split instead of fixed widths. Below 1024px, tab buttons become a dropdown. At very narrow widths, identity fields reflow into extra rows so nothing gets clipped.

The Adjustments tab label shortens to "Adjust" at narrow widths to fit.

Help toasts

On touch devices, the desktop help box is replaced by contextual toasts:

• Tap a field label to see a short description at the bottom of the screen.
• Tap and hold a control to read its help text without activating it. The toast stays visible while you hold, plus 3 seconds after release.

Ads

The tool uses Google AdSense auto ads (anchor banners) to help cover hosting costs. Supporters see no ads.

Automatic error reporting

When an import, pipeline, or export error occurs, an anonymous error report is sent automatically to help diagnose and fix things. These reports contain only technical data: the imported monster data (from public sources), parse flags, error messages, and build version. No personal info is included by default.

Enhanced telemetry (opt-in)

You can optionally enable enhanced telemetry in Account > Privacy. This adds browser/device info and any user-created ability text to error reports. Opt-in only, and you can change it any time.

Full privacy policy

For the complete rundown on data collection, cookies, advertising, and your rights, see the Built By Penguins Privacy Policy.

Licenses & attribution

Monster Modifier uses game content from the D&D System Reference Documents and third-party publishers under open licenses. See the Legal & Licenses page for full attribution and license text.