combat

name	combat
description	Resolve OSE combat — initiative, attacks, damage, saving throws, morale, spells, and death. Use when combat begins or a combat handoff block is provided.
allowed-tools	WebFetch Bash AskUserQuestion Read Glob Edit

Combat resolution for Old-School Essentials

Resolve combat step-by-step using SRD rules. Accepts the ENCOUNTER HANDOFF: COMBAT block from the encounter skill, or sets up combat manually.

Core principles

The referee's constitution governs all behavior. Read it before beginning play if it is not already in context. Additionally:

1. Look up rules from SRD — read the SRD map or monsters submap to find the right file, then Read it
2. Roll dice with roll.py — use uv run plugins/bx-referee/skills/referee/scripts/roll.py "<expr>"
3. Use AskUserQuestion only for administrative setup. During combat, present the status and wait for the player to declare actions
4. Update PARTY.md — track HP changes, expended resources, and death in the adventure's PARTY.md

Tool paths

• Dice roller: plugins/bx-referee/skills/referee/scripts/roll.py
• SRD map: plugins/bx-referee/skills/referee/references/srd_map.md (rules, classes, equipment, treasure)
• SRD monsters: plugins/bx-referee/skills/referee/references/srd_monsters.md
• SRD spells: plugins/bx-referee/skills/referee/references/srd_spells.md

Input format

This skill accepts either:

1. ENCOUNTER HANDOFF: COMBAT block from the encounter skill — parse environment, distance, surprise state, party stat blocks, and monster stat blocks directly from the block
2. Manual setup via $ARGUMENTS (e.g., /combat Goblin 3 dungeon 30) — if arguments are missing, use AskUserQuestion to gather: monster type, count, environment, and starting distance

Combat sequence

Step 0: Setup

• Parse the combat handoff block (if present in conversation), or gather details via AskUserQuestion

• Read SRD rules: use the SRD map to find and Read Combat.md, Combat_Tables.md, Morale_(Optional_Rule).md

• Read the monster page: use the monsters submap to find the file path, then Read it

• Read party data from the active adventure's PARTY.md (determine adventure path from conversation context — the game root and adventure name are in SESSION.md)

• Roll monster HP individually using their HD (if not already rolled from handoff)

• Present the battlefield summary: who's fighting, distance, surprise state

Step 1: Initiative

• Each side rolls 1d6 (group initiative per OSE rules)
• Surprised side loses first round (no actions)
• Ties: actions are simultaneous — both sides resolve before applying results
• Report initiative results

Step 2: Round start — declare party actions

• Display current status block (see status tracking format below)
• Wait for the player to declare actions for their characters. Do not present a menu of options.
• Record all declared actions before resolving any

Step 3: Movement phase

• Resolve movement for all combatants who declared movement
• Handle closing distance, retreating, positioning per srd/Combat.md

Step 4: Ranged attacks

• Resolve all ranged attacks (bows, thrown weapons, ranged spells)
• Use the attack resolution procedure (see below)
• Resolve per attack resolution procedure below

Step 5: Melee attacks

• Resolve per attack resolution procedure below

Step 6: Spell resolution

• Resolve spells cast this round
• Fetch the spell's SRD page if needed:

Read the spells submap (plugins/bx-referee/skills/referee/references/srd_spells.md) to find the spell file, then Read it.

• Saving throws where applicable: roll 1d20 vs target number from character/monster save table
• Apply spell effects (damage, conditions, buffs)
• Track spell durations in ongoing effects

Step 7: Monster actions

• Resolve monster attacks using the same attack resolution procedure
• Roll attacks and damage against PCs
• Apply special abilities (poison, breath weapon, etc. — fetch SRD as needed)
• Morale check: per srd/Morale_(Optional_Rule).md — check when first monster killed and when half incapacitated
• Report morale check results clearly

Step 8: Ongoing effects

• Resolve any per-round effects: burning, poison, disease, spell durations, potion durations
• Decrement duration counters; remove expired effects
• Apply per-round damage (e.g., poison dealing damage each round)
• Check for saving throws triggered by ongoing effects
• Report effect changes: expired effects, damage dealt, conditions applied or removed

Step 9: End of round / combat end

• Update and display the status block for all combatants
• Check end conditions:
  • All monsters dead or fled: victory — proceed to post-combat
  • All PCs dead or fled: defeat
  • Neither: display the status update and wait for the player to declare next round's actions. Loop to step 1
• Increment round counter

Attack resolution procedure

Use the attack procedure from srd/Combat.md and the attack matrix from srd/Combat_Tables.md. For each attack:

1. Look up THAC0 and calculate target number
2. Roll 1d20: uv run plugins/bx-referee/skills/referee/scripts/roll.py "1d20"
3. Apply modifiers (STR for melee, DEX for ranged, magic, situational)
4. On hit, roll damage and subtract from target HP

Spell and special ability handling

• When a PC casts a spell, fetch the relevant spell list page if not cached
• Apply spell effects exactly as described in the SRD
• Track spell slot expenditure — mark the slot as used
• Monster special abilities (poison, paralysis, breath weapons, etc.):
  • Fetch the monster SRD page for exact mechanics
  • Saving throws: roll 1d20 vs the appropriate save category and target number
  • Apply effects on failed save; note reduced/no effect on successful save

Ongoing effects tracking

Each active effect has:

• Source: what caused it (spell name, poison, ability)
• Target: who is affected
• Duration: rounds remaining (or "until save" / "permanent")
• Per-round effect: damage, condition, or other mechanical impact

At the start of each round (step 8), process all active effects:

1. Apply per-round damage or effects
2. Check for saving throws (if effect allows repeated saves)
3. Decrement duration
4. Remove expired effects and announce their removal

Status tracking format

Display this at the start of each round and at combat end:

## ROUND [n]
### Party
- [NAME] ([Class] [Level]): HP [current]/[max] | AC [value] | Att: [weapon] [damage] | EFFECTS: [list or none]

### Monsters
- [Type] #[n]: HP [current]/[max] | AC [value] | Att: [attacks] | EFFECTS: [list or none]
- [Type] #[n]: DEAD

Example:

## ROUND 3
### Party
- BLARG (Fighter 1): HP 5/7 | AC 1 | Att: sword 1d8+1
- SEDRA (Cleric 1): HP 3/4 | AC 4 | Att: mace 1d6 | EFFECTS: Bless (3 rds)

### Monsters
- Goblin #1: HP 1/3 | AC 6 | Att: sword 1d6 | EFFECTS: Poisoned (1d4/rd, 2 rds)
- Goblin #2: DEAD
- Goblin #3: HP 5/5 | AC 6 | Att: sword 1d6

Post-combat

After combat ends in victory:

1. Calculate XP: Sum XP values of all defeated monsters (from SRD stat block)
2. Treasure: If the player searches the bodies, check the monster SRD entry for treasure and present what they find
3. Award XP: Split the total XP evenly among surviving PCs, then apply each PC's prime requisite XP bonus percentage. The bonus is already recorded on each character's stat line in PARTY.md as (+N%) or (-N%) after the XP-to-next-level value. Multiply the base share by this modifier and round down. Report both the base share and each PC's adjusted total.
4. Update PARTY.md using Edit tool:
   • Current HP (update HP current/max)
   • Expended spell slots or consumable items
   • XP gained (adjusted per-PC totals from step 3)
   • Dead PCs: append | STATUS: DEAD to their first line
5. Level-up check: After updating XP, check each surviving PC: if their new XP total ≥ the next-level threshold (the value after / in XP current/next), hand off to the character skill for advancement:
   • Skill "character" "level-up <adventure-path>" — pass the adventure directory path
   • Only one level gain per session is permitted. If XP would push a PC two or more levels, cap their XP at 1 below the threshold for the level after next (see srd/Advancement.md, "Maximum XP in One Session")
   • After the character skill returns, re-read PARTY.md for updated stats before continuing

SRD page slugs reference

Core combat rules:

• Combat
• Combat_Tables
• Morale_(Optional_Rule)

Spell lists (fetch as needed):

• Cleric_Spells
• Magic-User_Spells

Monster pages use the monster name as slug (e.g., Goblin, Ogre, Black_Dragon).