Corrupted Ancient Dragon boss guide: weaknesses & drops (7DSO)

Boss

Corrupted Ancient Dragon

Difficulty

Abyss

Min. BP82,015

Players

Stats

HP3,707,608

ATK22,107

DEF12,084

Weaknesses

Dark20%

Holy20%

Resistances

All Elements15%

Zone

Solgres Boss Arena

Scale Hardened With MagicIn-game tip

All element damage greatly decreases. The applied Damage Reduction decreases each time a Burst activates. Applies only once per elemental burst. This effect resets when the phase shifts.

Hold your Elemental Bursts: each Burst you pop in this phase shaves off the boss's damage reduction, so stagger your bursts to grind it down rather than dumping them all at once.
Lead with Holy DPS to exploit its weakness faster, then unload bursts once the reduction has dropped a few stacks.

Skin Enveloped in MagicIn-game tip

All Elemental Burst Resistance increases. All Elemental Resistances decrease when inflicted with a debuff. Applies up to 5 times per one element. This effect resets when the phase shifts.

Stack debuffs fast: every debuff drops its Elemental Resistances (up to 5 per element), so prioritize Holy units and debuff-heavy kits to soften it before you commit real damage.
Save your big Holy bursts for after you've layered debuffs, since burst resistance is up early and falls off as you pile on the stacks.

OverloadIn-game tip

Completely filling the Daze Gauge while it's preparing for a powerful attack will inflict stun.

When it telegraphs the long arena-wide cast, pour everything into the Daze Gauge: filling it before the hit lands stuns the dragon and skips the nuke entirely.
Bring a daze-heavy comp and bank gauge pressure for this window, then chain your highest Holy burst into the open stun.

Moveset — the real numbers

Its AI decides when it uses what, so there is no fixed rotation to memorize — but every damage %, reach, duration and crowd control below is exact.

Attack	Damage (% of ATK)	Reach	Duration	Control
Arena nukeThe big one with a long wind-up that fills almost the whole arena. This is the cast you want to dump the Daze Gauge into during Overload.	—	100m	27.78s	—
Piercing breathA long straight beam that staggers. Stand off to the side, never directly in front of the head.	—	60m	5.58s	Stagger
Triple beam lineComes in a set of three back-to-back straight lines. Sidestep, don't try to outrun it.	—	40m	7.83s	—
Phase-shift slamTwo-hit knock-up that fires on the phase change. Bait it, then re-engage once you land.	—	10m	10.67s	AirBorne
Rapid stomp flurryLong burst of fast tight hits in melee range. Roll out early or it chunks you down.	—	5m	9s	—
Sustained quakeDrawn-out tick pulses on the same spot. Reposition once and stay out of the circle.	—	5m	16s	—
Nested ringsThree shrinking rings that hit harder the closer they get. Run toward the boss to slip the inner ring.	—	30m	14.01s	AirBorne
Frontal cone sprayA wide multi-hit cone in front. Get behind or to the flank to dodge the whole fan.	—	35m	9.73s	—
Aerial barrageAirborne rain of many small hits in tight circles. Keep moving while it's overhead.	—	5m	9.6s	—
Landing slamThe knock-up it drops when it comes back down. Watch the marker and clear the impact spot.	—	8m	11.12s	AirBorne
Lunge biteA fast forward line poke with knock-up. Cheap punish window right after it whiffs.	—	13m	4.83s	AirBorne

The phase descriptions are the official in-game boss tips; the tactical bullet points are our advice. Every damage value, reach, duration and crowd-control effect in the moveset is the boss's real in-game value. Attack names are descriptive labels.