Zerg Hatchery

{t}: Add {b} or {g}.

Larva Incubation - At the beginning of
combat if this land wasn't tapped for mana,
add 1 Larva counter to this land.

Mutate into Lair - At the beginning of your upkeep if this land has over 3 Larva counters, you may choose to remove all larva counters and transform this land into a Zerg Lair.