Corruption

Enchant target creature you control. Whenever
your life is 10 or less, you may sacrifice that
creature. Target opponent or creature is dealt
damage equal to sacrificed creature's converted
mana cost.
Cainhurst Vileblood Covenant (enchanted
creature has "Vileblood" added to its subtypes,
except if it is an Executioner).
"Pledgers to this oath are the Cainhurst Vilebloods,
hunters of blood who find dregs for their Queen in coldblood, particularly in that of hunters."