Yoot, the Killer

Dumbness (this creature cannot attack or block)
{t}: Target creature gets +1/+0 or +0/+1, then that creature loses dumbness until end of turn.
For the rest of the game, you can't cast spells. At the beginning of each of your upkeeps or whenever your opponent casts a spell, create a non-legendary copy of Yoot without this ability.