Fever Worm

Parasitize - Creature on top gains haste and
"This creature must attack each turn if able." At
the beginning of battle, before attackers, it gains
+3/+0 until end of turn. (When this creature
enters the battlefield, put it under target non-artficact creature. While under a creature, it cannot attack, be attacked, and block. It can still be targetted by spells
and abilities.)
Whenever creature on top attacks, deal 2 damage
to its controller.