Flood Basin
Land (Rare)

At the beginning of your end step, if you didn't cast any spells this turn, Flood Basin deals 1 damage to you.

When Flood Basin enters the battlefield, put a land you control on the bottom of its owner's library.

Tap: Add GU to your mana pool.

GU: Flood Basin becomes a 2/1 blue and green Shapeshifter creature until end of turn. It's still a land.

James Sweet