Crucio

Deal 3 damage to target creature, put 2 stun counters on it, whenever a stun counter is removed put 2 -1/-1 counters on the creature they were removed from.

Harry shouted, "Crucio!". The Death Eater was lifted off his feet. He writhed through the air like a drowning man, thrashing and howling in pain,
and then, with a crunch and a shattering of glass, he smashed into the front of a bookcase and crumpled, insensible, to the floor.