Abysswalkers

At the beginning of each combat step
Abysswalkers fight target creature.
Whenever Abysswalkers takes combat damage
you create a token copy of Abysswalkers and
you lose 2 life.
{b}{r}, Sacrifice a knight: Abysswalkers gains
+2/+0 until end of turn.
Whenever a knight dies, each opponent loses 1
life and you gain 1 life for each life lost this way.