Underground Oasis enters the battlefield tapped unless you sacrifice an artifact land.
, : Add to your mana pool.
: Underground Oasis becomes a 2/1 black and green Horror creature until end of turn. It's still a land.
, 
: Add 
to your mana pool., : Add to your mana pool.: Underground Oasis becomes a 2/1 black and green Horror creature until end of turn. It's still a land.
