The minionKill hook

Hooks.on("minion-bang.minionKill", event => { /* ... */ });

Minion! calls Hooks.callAll("minion-bang.minionKill", event) once for each minion whose hit points go from above 0 to 0, after the new hit points are saved. An attack that drops its target and three more minions by overkill makes four calls.

When it's called

• Only on the active GM's client. When another GM applies the damage, Minion! sends the event to the active GM through socketlib.
• Once the update that sets the hit points to 0 has gone through, however long that takes. If Minion! expects a death and the update never arrives, it gives up after ten minutes.
• Never twice for the same death. The active GM remembers the last 500 eventId values.

It's not called when:

• the minion was already at 0 hit points;
• someone sets the Dead status or the defeated mark by hand;
• a token is deleted or added to a combat, or the world reloads;
• an overkill is cancelled;
• the update fails.

A minion that's revived and killed again gets a new eventId. Past deaths aren't replayed, so a listener registered late misses them.

The event

Every field is always present. When Minion! doesn't know a value, it's null.

{
  schemaVersion: 1,
  eventId: "…",        // this death; also saved in flags.minion-bang.deathId
  workflowId: "…",     // uuid of the attack's chat card; null if unknown
  combatId: "…",       // null outside combat
  sceneId: "…",
  round: 2,            // null outside combat
  turn: 0,             // Foundry's turn index, can be 0; null outside combat
  attacker: {          // null if unknown
    actorId: "…", actorUuid: "…", tokenUuid: "…", name: "Akra"
  },
  victim: {
    actorId: "…", actorUuid: "…", tokenUuid: "…", name: "Goblin Lackey 3",
    cr: 0.25,          // null if the actor has none
    minionsPerStandard: 5   // the maximum band size for that CR in Minion!'s table
  },
  itemUuid: "…",       // the weapon or spell; null if unknown
  cause: "direct"      // "direct", "overkill" or "other"
}

Field	Notes
eventId	Unique for each death. The same value is saved in flags.minion-bang.deathId on the minion, in the same update as the hit points.
workflowId	Shared by every victim of one attack. It's the uuid of the chat card, so each use of an item has its own.
combatId, round, turn	null when no combat has started. Filter on them if you only want kills made in combat.
victim.cr	null when the actor has no challenge rating. Never 0 as a stand-in.
victim.minionsPerStandard	The maximum band size for that challenge rating in the band size table, including the GM's edits. null when cr is null.

The three causes

cause	Meaning	attacker
direct	The minion an attack, spell or effect hit, dropped by the Minion trait.	Present when Midi-QOL reports the attacker.
overkill	A minion taken down by another minion's overkill.	The player character who made it.
other	Hit points reached 0 some other way: typed by hand, or damage with no Midi-QOL data.	null

For other, Minion! needs the hit points from before the change to be sure the minion just died. If it can't tell, it sends nothing.

Example

const kills = new Map();

Hooks.on("minion-bang.minionKill", event => {
  if (!event.attacker) return;
  const total = (kills.get(event.attacker.name) ?? 0) + 1;
  kills.set(event.attacker.name, total);
  console.log(`${event.attacker.name}: ${total} minion kills (${event.cause})`);
});

This counts one kill per call. If your module saves kills, save each eventId as well and skip any eventId you already have.