Walking Ballista + Unspeakable Symbol + Furnace of Rath + Quest for Pure Flame

Walking Ballista

Unspeakable Symbol

Furnace of Rath

Quest for Pure Flame

How it works

1. Activate Quest for Pure Flame by removing four quest counters from it and sacrificing it, doubling all damage dealt by sources you control this turn.
2. Give Walking Ballista lifelink, if needed.
3. If Walking Ballista has less than two +1/+1 counters on it, activate Unspeakable Symbol by paying 3 life, putting a +1/+1 counter on Walking Ballista.
4. Activate Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 4 damage to an opponent or a permanent an opponent controls, and causing you to gain 4 life.
5. Repeat from step 3.