Monster Creation

Creating compelling monsters is essential for Game Masters to challenge players and bring their world to life. This section provides guidelines for designing balanced and interesting creatures.

Monster Statistics

Basic Statistics

Challenge Rating (CR)

CR indicates the difficulty of a monster relative to party level. A CR 1 monster is a moderate challenge for a party of four 1st-level characters.

Hit Points

Determines how much damage a monster can sustain. Use hit dice based on size:

• Tiny: d4
• Small: d6
• Medium: d8
• Large: d10
• Huge: d12
• Gargantuan: d20

Hit Points = (Hit Dice × average roll) + (Hit Dice × Constitution modifier)

Armor Class (AC)

Determines how hard the monster is to hit:

• 5-7: Very easy to hit
• 8-11: Easy to hit
• 12-14: Average
• 15-17: Hard to hit
• 18-20: Very hard to hit
• 21+: Extremely hard to hit

Speed

How far the monster can move in a round. Include special movement types (climb, fly, swim) if applicable.

Ability Scores

Assign ability scores appropriate to the creature's concept:

• Strength: Physical power for melee attacks
• Dexterity: Agility for AC and ranged attacks
• Constitution: Durability for hit points
• Intelligence: Reasoning and knowledge
• Wisdom: Awareness and perception
• Charisma: Force of personality

Proficiencies

Saving Throws

Most monsters have proficiency in 0-3 saving throws, typically those related to their strengths.

Skills

Grant skill proficiencies that match the monster's concept and capabilities.

Damage Modifiers

• Resistances: Monster takes half damage from specified types
• Immunities: Monster takes no damage from specified types
• Vulnerabilities: Monster takes double damage from specified types

Condition Immunities

List any conditions the monster is immune to (charmed, frightened, paralyzed, poisoned, etc.).

Senses

• Darkvision: See in darkness to a certain range
• Blindsight: Perceive surroundings without sight
• Tremorsense: Detect vibrations in the ground
• Truesight: See through illusions and darkness
• Passive Perception: 10 + Wisdom (Perception) modifier

Languages

List languages the monster understands and speaks. Many monsters understand but cannot speak.

Monster Abilities

Special Traits

Passive abilities that are always active:

• Pack Tactics: Advantage when allies are near
• Magic Resistance: Advantage on saves vs. spells
• Regeneration: Regain hit points each round
• Legendary Resistance: Automatically succeed on saves

Actions

What the monster can do on its turn:

Multiattack

Allows multiple attacks in one action. Common for CR 5+ creatures.

Attacks

Define attack bonus, reach/range, and damage: Attack Bonus = Proficiency Bonus + Ability Modifier

Spellcasting

If the monster casts spells, specify:

• Spellcasting ability and save DC
• Spell slots or at-will spells
• List of known spells

Bonus Actions

Quick actions that don't use the main action.

Reactions

Triggered responses to specific events (opportunity attacks, counterspell, etc.).

Legendary Actions

Powerful creatures (CR 10+) can take 1-3 legendary actions at the end of another creature's turn:

• Cost varies (1-3 points from a pool of 3)
• Only one legendary action at a time
• Only at the end of another creature's turn
• Regain all at the start of the creature's turn

Lair Actions

On initiative count 20 in the creature's lair, it can cause environmental effects.

Regional Effects

The monster's presence alters the region around its lair.

Balancing Monsters

Offensive CR

Based on average damage per round and attack bonus:

1. Calculate average damage per round
2. Find the CR from the damage table
3. Adjust based on attack bonus vs. expected AC

Defensive CR

Based on hit points and armor class:

1. Use hit points to find base CR
2. Adjust based on AC vs. expected attack bonus
3. Factor in resistances and immunities

Final CR

Average the offensive and defensive CRs, then adjust based on:

• Special abilities
• Saving throw proficiencies
• High ability scores
• Condition immunities

Monster Roles

Brute

High damage, high hit points, low AC. Straightforward combatants.

Skirmisher

Mobile threats that dart in and out of combat. Hit-and-run tactics.

Controller

Manipulates the battlefield with area effects, conditions, and terrain.

Support

Buffs allies, debuffs enemies, heals, and coordinates.

Artillery

Ranged attackers who stay back and deal damage from afar.

Defender

Protects allies and locks down enemies. High AC and control abilities.

Design Tips

Give Interesting Abilities

Avoid monsters that only make basic attacks. Add special traits, reactions, or legendary actions.

Consider Action Economy

Multiple weaker monsters often challenge parties more than one strong monster.

Match Theme

Abilities should reinforce the monster's concept and ecology.

Test and Iterate

Playtest your monsters and adjust based on how they perform in actual combat.

Vary Defenses

Use different AC values, resistances, and immunities to prevent one strategy from dominating.

Tell a Story

Give monsters behaviors, tactics, and motivations that make sense for their nature.