d20-combat

What this skill does

# Combat Management Skill

Use this skill to guide d20-style combat encounters. Combat follows a structured turn order determined by initiative, with each participant taking actions to attack, defend, cast spells, or interact with the environment.

## Starting Combat

When combat begins, establish these elements in order:

1. **Establish positions** - Determine where combatants are located relative to each other
2. **Roll initiative** - All combatants roll to determine turn order
3. **Take turns** - Proceed through rounds until combat ends

### Rolling Initiative

Each combatant rolls initiative to determine turn order:

```
Initiative = d20 + Dexterity modifier
```

Use the mcp__corvran__roll_dice tool for initiative rolls:

```
Use the mcp__corvran__roll_dice tool:
{ "groups": [{ "n": 1, "d": 20 }], "modifier": 2 }
```

Order combatants from highest to lowest initiative. Ties between players are resolved by player choice; ties between monsters use GM discretion.

**Surprise**: If a combatant is surprised (unaware combat is starting), they have Disadvantage on their initiative roll.

## Turn Structure

On each turn, a combatant can take the following in any order:

### Movement
Move up to your Speed (typically 30 feet). Movement can be split before and after your action.

### Action (pick one)
| Action | Effect |
|--------|--------|
| **Attack** | Make one attack with a weapon or Unarmed Strike |
| **Cast a Spell** | Cast a spell with a casting time of 1 action |
| **Dash** | Gain extra movement equal to your Speed |
| **Disengage** | Your movement doesn't provoke Opportunity Attacks this turn |
| **Dodge** | Attack rolls against you have Disadvantage; DEX saves have Advantage |
| **Help** | Give an ally Advantage on their next attack or ability check |
| **Hide** | Make a Stealth check to become hidden |
| **Ready** | Prepare an action to trigger on a specific condition |
| **Search** | Make a Perception, Insight, Medicine, or Survival check |
| **Study** | Make an Intelligence check to recall information |
| **Utilize** | Use a nonmagical object |

### Bonus Action
Only available if a feature, spell, or ability grants one. Examples include:
- Two-Weapon Fighting (attack with off-hand weapon)
- Cunning Action (Rogue)
- Certain spells (Healing Word, Misty Step)

### Reaction (once per round)
Triggered by specific events. Resets at the start of your next turn.
- **Opportunity Attack**: When a creature leaves your reach
- **Ready**: The trigger you defined occurs
- **Certain spells**: Shield, Counterspell

### Free Interaction
One free object interaction per turn (draw a weapon, open a door, pick up an item).

## Making Attack Rolls

To attack, roll d20 and add modifiers, then compare to target's Armor Class (AC):

```
Attack Roll = d20 + Ability Modifier + Proficiency Bonus (if proficient)
```

### Attack Types

| Attack Type | Ability Used |
|-------------|--------------|
| Melee weapon | Strength (or DEX with Finesse) |
| Ranged weapon | Dexterity |
| Unarmed Strike | Strength |
| Spell attack | Spellcasting ability |

### Attack Roll Outcomes

- **Roll >= AC**: Hit. Roll damage.
- **Roll < AC**: Miss. No damage.
- **Natural 20**: Critical Hit. Always hits. Double all damage dice.
- **Natural 1**: Automatic miss regardless of modifiers.

Use the mcp__corvran__roll_dice tool for attack rolls:

```
Use the mcp__corvran__roll_dice tool:
{ "groups": [{ "n": 1, "d": 20 }], "modifier": 5 }
```

### Advantage and Disadvantage

- **Advantage**: Roll 2d20, use the higher result
- **Disadvantage**: Roll 2d20, use the lower result
- Multiple sources don't stack
- Having both cancels to a normal roll

Common sources of Advantage:
- Attacking while hidden/invisible
- Target is prone (melee attacks)
- Target can't see you
- Help action from an ally

Common sources of Disadvantage:
- Target is prone (ranged attacks)
- You can't see the target
- Ranged attack while enemy is within 5 feet
- Certain conditions (Frightened, Poisoned, Restrained)

## Damage Rolls

On a hit, roll the weapon's damage dice plus your ability modifier:

```
Damage = Weapon Dice + Ability Modifier
```

Use the mcp__corvran__roll_dice tool for damage:

```
Use the mcp__corvran__roll_dice tool:
{ "groups": [{ "n": 1, "d": 8 }], "modifier": 3 }
```

### Common Weapon Damage

| Weapon | Damage | Type |
|--------|--------|------|
| Dagger | 1d4 + modifier | Piercing |
| Shortsword | 1d6 + modifier | Piercing |
| Longsword | 1d8 + modifier | Slashing |
| Greatsword | 2d6 + modifier | Slashing |
| Shortbow | 1d6 + modifier | Piercing |
| Longbow | 1d8 + modifier | Piercing |

### Critical Hit Damage

Roll all damage dice twice, then add modifiers once:

```
Critical Damage = (Weapon Dice x 2) + Ability Modifier
```

Example: Longsword critical = 2d8 + STR modifier

## Opportunity Attacks

When a creature you can see leaves your melee reach using its movement, action, or reaction, you may use your reaction to make one melee attack against it.

**Avoiding Opportunity Attacks**:
- Take the Disengage action
- Teleport
- Be moved by an external force (not your own movement)

## Special Combat Situations

### Cover
| Cover Type | Benefit |
|------------|---------|
| Half Cover | +2 AC and DEX saves |
| Three-Quarters Cover | +5 AC and DEX saves |
| Total Cover | Can't be targeted directly |

### Ranged Attacks in Melee
Making a ranged attack while within 5 feet of a hostile creature imposes Disadvantage.

### Two-Weapon Fighting
When you take the Attack action with a light melee weapon, you can use your bonus action to attack with a different light melee weapon in your other hand. Don't add your ability modifier to the damage of the bonus attack (unless negative).

### Grappling
Use an Unarmed Strike to grapple. Target makes STR or DEX save (their choice) vs DC 8 + your STR modifier + proficiency bonus. On failure, target has the Grappled condition.

### Shoving
Use an Unarmed Strike to shove. Same save as grappling. On failure, push target 5 feet or knock them Prone.

## Conditions Quick Reference

Combat frequently applies conditions. See `references/conditions.md` for full details.

| Condition | Key Effect |
|-----------|------------|
| **Blinded** | Auto-fail sight checks; attacks have Disadvantage |
| **Charmed** | Can't attack charmer; charmer has social Advantage |
| **Frightened** | Disadvantage on attacks/checks while source visible |
| **Grappled** | Speed 0; Disadvantage on attacks vs non-grappler |
| **Incapacitated** | Can't take actions, bonus actions, or reactions |
| **Invisible** | Advantage on attacks; attacks against have Disadvantage |
| **Paralyzed** | Incapacitated; auto-fail STR/DEX saves; auto-crit if hit |
| **Prone** | Disadvantage on attacks; melee attacks have Advantage against |
| **Restrained** | Speed 0; attacks have Disadvantage; Disadvantage on DEX saves |
| **Stunned** | Incapacitated; auto-fail STR/DEX saves |
| **Unconscious** | Incapacitated; Prone; auto-fail STR/DEX saves; auto-crit |

## Death and Dying

### Dropping to 0 HP
- **Monsters**: Die immediately (unless GM rules otherwise)
- **Player Characters**: Fall unconscious and begin making Death Saving Throws

### Death Saving Throws
At the start of each turn while at 0 HP, roll d20:
- **10 or higher**: Success
- **Below 10**: Failure
- **Three successes**: Become Stable (unconscious but not dying)
- **Three failures**: Die
- **Natural 1**: Two failures
- **Natural 20**: Regain 1 HP and consciousness

### Stabilizing
Use the Help action with a DC 10 Medicine check to stabilize a dying creature. A stable creature regains 1 HP after 1d4 hours.

## Encounter Templates

For encounter setup and tracking, see `references/encounter-template.md` and `references/encounter-example.md`.

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*Combat rules derived from SRD 5.2.1, licensed under CC-BY-4.0.*