Power of the Vliste-Staba

Enchant Creature
Enchanted creature has "{1}{g}, {t}: prevent X
darkening damage dealt to any target and put
X darkening counters on enchanted creature."
At the beginning of your upkeep, if enchanted
creature has any darkening counters, remove all
counters from it and deals X damage to target
permanent an opponent controls where X is
equal to the darkening counters removed this
way.