Azrakh doesn't bargain the way the temple's older devil-cults did. He brands his marks instead and lets the debt collect itself - and when three different people are burning at once, he considers the account closed.
A random nearby enemy is branded with a stacking fire debuff (cap 3 stacks on that target, tracked locally on the target itself, not on Azrakh).
That mark detonates immediately for bonus fire damage scaled to its stack count.
His epic spell answers, aimed at whichever marked enemy is currently stacked highest, scaled by that count. No prior mechanic here tracks a resource spread across multiple TARGETS rather than banked on the boss or one victim - Segovax's devil pact (round 10) is a self-cost gamble with no target-side bookkeeping at all.
Every standing Cindermark is wiped so the spread has to build again from zero.
Karrion Temple's real ceiling stood at CR17 (Grommash Kar, round 9); Azrakh is pitched one notch above at CR18, into the area's most open Sparky headroom of any target this round (4 free slots before this boss).
He is the bestiary's first Hellfire Warlock - an ability-based PRC (no dedicated spells.2da column), cloned from humanmerc002, an existing Jasperre-AI human donor.
Real Epic Spell: Ruin (id 640/878) - Karrion Temple had no standing epic spell before this boss; Ruin's single-target devastation was framed as the closing of an infernal ledger rather than a scheduled climax.