Roh, Vatic Swarmlord

Roh, Vatic Swarmlord can't be blocked by white creatures.
Black creatures you control can't be blocked by white creatures.
Whenever Roh, Vatic Swarmlord deals combat damage to a player, put a +1/+1 counter on it. If Roh, Vatic Swarmlord has two or more +1/+1 counters on it, red and black creatures have flash during your turn.