Horizon Pool enters the battlefield tapped.
: Add or to your mana pool.
Put Horizon Pool on top of your library: Add to your mana pool.
: Horizon Pool becomes a 0/4 white and black Bird creature with defender until end of turn. It's still a land.
: Add 
or 
to your mana pool.
to your mana pool. : Horizon Pool becomes a 0/4 white and black Bird creature with defender until end of turn. It's still a land.
