Tolarian Cloaker

Tolarian Cloaker is destroyed if you do not
control a Mountain.
If you control an Island and Tolarian Cloaker is untapped, it gains +0/+3 and "Whenever
Tolarian Cloaker blocks 1 or more creatures,
both it and the creatures it's blocking phase out." Whenever a creature blocked by Tolarian Cloaker phases in, it deals damage to itself equal to half
its power rounded up.