Entity Deal Damage

ENTITY_DEAL_DAMAGE adds progress from damage dealt to matching entities.

quests: # Root task configuration.
  levels: # Level entries.
    18: # Target level.
      requirements: # Requirement list.
        rules0: # Unique rule id.
          type: "ENTITY_DEAL_DAMAGE" # Listen for player damage dealt to entities.
          entity: "ZOMBIE" # Entity type that should receive damage.
          amount: "1" # Damage multiplier used by the source parser.
          required: "25" # Required damage/progress target.
        description: # Requirement descriptions.
          0: "%status%<reset> <gray>Deal 25 damage to zombies</gray> <white>({currentProgress}/{maxProgress})</white>" # Description for rules0.

Use this when you want damage dealt to matter, not just final kills.