He starts counting the second the fight starts, out loud, and he does not stop for anything. Nine. Eight. Seven. It is not a threat. It is a schedule, and it does not care whether you are ready when it runs out.
The count ticks down by one, spoken aloud - the first true enrage clock in this bestiary. Every prior timer here (Ilqaeth's doors, Malbrek's recoil) is something the party can stall or dodge around; this one just runs.
Approximated as a real critical hit, since a plain OnDamaged event carries no clean crit flag - the count is pushed back up by one, capped at nine. It is the only slowdown that exists.
His epic spell detonates in a 12m burst centred on himself, full damage to everyone caught in it including his own position, and the count resets to nine so the sentence begins again.
Cathedral Level 2's real ceiling was Malvenna Ash, the God-Thief at CR15 (round 1); Dravos is pitched one notch above at CR16, into the area's biggest remaining headroom - 6 free Sparky slots, more than any other target this round.
He is the bestiary's first Fist of Hextor - a Cleric-advancing prestige class with no dedicated column, so his list sits on the Cleric entry he advances from, matching the 'stacks onto the base caster' convention used for Force Missile Mage and Abjurant Champion before him. Cathedral Level 2 already had a fallen priest (Malvenna); Dravos is a zealot of a specific god of tyranny rather than a generic apostate.
Real Epic Spell: Hellball (id 636/876) - the most aggressive of the five HotU epic spells, matched here to the one boss whose entire mechanic is an unavoidable detonation on a fixed clock rather than a threshold the party controls.