Mimic Oasis

Unless you control a face-down card, Mimic Oasis
enters the battlefield tapped.

{t}: add {1} to your mana pool.

When a creature you control is flipped face-down,
you can {t}: target a nonland permanent, destroy it.

When a face-down card you control is flipped face-up
and is a creature, each opponent loses life equal to
that creature's power plus its toughness.