At the beginning of your upkeep, Doomgape triggers, causing you to sacrifice Serra Avatar and gain life equal to its toughness.
Sanguine Bond triggers, causing an opponent to lose life equal to the life you gained.

Near-infinite lifegain

Near-infinite lifeloss for target opponent

Doomgape

Serra Avatar

Sanguine Bond

At the beginning of your upkeep, Doomgape triggers, causing you to sacrifice Soul of Eternity and gain life equal to its toughness.
Sanguine Bond triggers, causing an opponent to lose life equal to the life you gained.

Soul of Eternity

Pay {0} to activate Outrider en-Kor, targeting Task Force.
Task Force triggers, giving itself +0/+3 untill end of turn.
Repeat steps 1-2 untill Task Force has infinite toughness.
Sacrifice Task Force to Doomgape, gaining life equal to its toughness.

Combos with "Doomgape"