Mismagius

Its muttered curses can cause awful headaches or terrifying visions that torment others.

Ability — Spiteful Magic: If this Pokémon has full HP and is Knocked Out by damage from an attack from your opponent's Pokémon, put 8 damage counters on the Attacking Pokémon.

Eerie Voice: Put 2 damage counters on each of your opponent's Pokémon.