Exponential Mob

When Exponential Mob enters the battlefield, put a rally counter on it.
At the beginning of your upkeep, put a 1/1 blue and black human creature token onto the battlefield for each rally counter on Exponential Mob.
{t}, sacrifice a creature: Put a rally counter on Exponential Mob if the sacrificed creature was blue or black. (Put two rally counters on if the sacrificed creature was blue and black.)