Obsidian Hollows
Land-Swamp Forest (Rare)

(Tap: Add B or G to your mana pool.)

Obsidian Hollows enters the battlefield tapped.

Tap, Sacrifice a Swamp: Add BB to your mana pool.

2, Tap: Target land becomes a 3/3 green Squirrel Beast creature until end of turn. It's still a land.

Allan Chippy