"Killer variables," says Secrets.
Code:
$killer_damage
$killer_id
$killer_skill
$killer_spell
Something like this can be done for players killed by players.
Code:
sub EVENT_DEATH_COMPLETE {
if ($entity_list->GetMobByID($killer_id) && $entity_list->GetMobByID($killer_id)->IsClient()) {
##Do whatever
}
}