Treetop Springs
Land (Rare)

Treetop Springs enters the battlefield tapped unless you reveal a land card from your hand.

Tap: Add R or G to your mana pool. Treetop Springs deals 1 damage to you.

RG: Treetop Springs becomes a 2/1 green and red Elf Squirrel creature until end of turn. It's still a land.

Douglas Moeller