Diregraf Colossus enters the battlefield with a +1/+1 counter on it for each Zombie card in your graveyard.
Whenever you cast a Zombie spell, create a tapped 2/2 black Zombie creature token.
4/8/2016 If Diregraf Colossus enters the battlefield from your graveyard, its first ability will count itself among the Zombie cards in your graveyard. Similarly, if it enters the battlefield at the same time as another Zombie card enters the battlefield from your graveyard, the ability will count that other Zombie.
4/8/2016 Diregraf Colossus’s last ability won’t trigger when you cast it because it’s not on the battlefield yet.