Whenever you cast an instant or sorcery spell, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
At the beginning of your upkeep, if you control three or more creature tokens, you may transform this creature.

Creature tokens you control lose all abilities and have base power and toughness 3/3.
At the beginning of your upkeep, you may transform this artifact.