Quest for Pure Flame by removing four quest counters from it and sacrificing it.
Cast
Malignus by paying ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) . It'll enter with power equal to half the highest life total among your opponents, rounded up.
When
Malignus enters,
Champion of the Path triggers, causing
Malignus to deal damage equal to its power doubled to each opponent due to
Quest for Pure Flame.
Notes
Malignus also makes the damage unpreventable due to its static effect. This combo should result in each opponent losing the game except in niche circumstances.