Faerie Conclave enters the battlefield tapped. {T}: Add {U}. {1}{U}: Faerie Conclave becomes a 2/1 blue Faerie creature with flying until end of turn. It's still a land.

Forbidding Watchtower enters the battlefield tapped. {T}: Add {W}. {1}{W}: Forbidding Watchtower becomes a 1/5 white Soldier creature until end of turn. It's still a land.

Ghitu Encampment enters the battlefield tapped. {T}: Add {R}. {1}{R}: Ghitu Encampment becomes a 2/1 red Warrior creature with first strike until end of turn. It's still a land. (It deals combat damage before creatures without first strike.)

Spawning Pool enters the battlefield tapped. {T}: Add {B}. {1}{B}: Spawning Pool becomes a 1/1 black Skeleton creature with "{B}: Regenerate this creature" until end of turn. It's still a land. (If it regenerates, the next time it would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)