Anti-Venom, Horrifying Healer + Agatha's Soul Cauldron + Quest for Pure Flame + Deathbringer Thoctar

Anti-Venom, Horrifying Healer

Agatha's Soul Cauldron

Quest for Pure Flame

Deathbringer Thoctar

How it works

1. Activate Quest for Pure Flame by removing four quest counters from it and sacrificing it, doubling the damage sources you control will deal this turn.
2. Activate Anti-Venom using Deathbringer Thoctar's ability by removing a +1/+1 counter from it, targeting itself and putting two +1/+1 counters on it due to its replacement effect and Quest for Pure Flame.
3. Activate Anti-Venom using Deathbringer Thoctar's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
4. Repeat from step 2.

This loop turns self-inflicted damage into an unstoppable engine of destruction by using Agatha's Soul Cauldron to grant Deathbringer Thoctar's activated ability to Anti-Venom, Horrifying Healer. Because Anti-Venom converts any damage dealt to it into an equal number of +1/+1 counters instead, you can continually pay the cost of removing a counter to ping itself, netting a positive gain of counters each time. With Quest for Pure Flame having already doubled the damage dealt this turn, those self-inflicted pings snowball into an explosive surplus of counters that can then be redirected to close out the game.