Unstable Den enters the battlefield tapped.
, : Add to your mana pool.
: Unstable Den becomes a 0/4 red and white Giant creature with defender until end of turn. It's still a land.
, 
: Add 
to your mana pool., : Add to your mana pool.
: Unstable Den becomes a 0/4 red and white Giant creature with defender until end of turn. It's still a land.
