Reef Clump
Land (Rare)

At the beginning of your upkeep, Reef Clump deals 2 damage to target creature you control.

Tap: Add G or U to your mana pool.

Sacrifice Reef Clump: Add G or U to your mana pool.

2G: Reef Clump becomes a 2/2 green and blue Crab creature with trample until end of turn. It's still a land.

Allan Staples