Spawning Pool

Spawning Pool enters the battlefield tapped.
{1},{t}: Add a Progress counter to Spawning pool
.
When Spawning pool is tapped, create a 1/1
Zerg Drone token.
When Spawning pool has three Progress counter,
all Zerg Creatures get +1/+0.
When Spawning pool has seven Progress counter,
all Zerg Creatures get Trample.