Grass-Chamber
Land (Rare)

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

Tap: Add G to your mana pool. If you played a land this turn, Add U to your mana pool instead.

1U: Grass-Chamber becomes a 1/1 green and blue Leech creature with flying until end of turn. It's still a land.

Eric Deschamps