(: Add or to your mana pool.)
Blackcleave Key enters the battlefield tapped.
: Blackcleave Key becomes a 2/1 black and blue Skeleton Cleric creature until end of turn. It's still a land.
: Add 
or 
to your mana pool.): Blackcleave Key becomes a 2/1 black and blue Skeleton Cleric creature until end of turn. It's still a land.
