The Dread Cellar
Abandoned Imperial prison taken over by the Waking Flame. Three main bosses, each with its own hard mode banner, plus three optional guardian bosses that you can later summon to help in fights.
- Hard mode banners unlock in order. Cyronin HM needs a Scorion Broodlord HM kill first, and Magma Incarnate HM needs HM kills on both earlier bosses.
- Secret guardians (Purgator, Undertaker, Grim Warden): each one is behind a trapdoor. Carry braziers (a synergy) to it, open the portal by activating the crystals at the same time, then light the braziers by the guardian stone to start the fight. A ghost, Vitellia Laenius, explains each step.
- After each guardian dies, you get a permanent buff and can click its Guardian Stone in boss rooms. It summons the guardian for 1 minute and resurrects dead allies. Save it for a wipe-saver.
- Bug: some doors can show as 'Impossible' and block progress. Reset the instance if that happens.
Purgator
Secret bossHow to spawn: First guardian, in the area before the Scorion Broodlord. Take braziers to the trapdoor, activate the crystals together, go through the portal, light the braziers by the orange guardian stone, then touch the stone.
- Meteor: after his overhead hammer slam, a meteor lands on each player. Stay spread. Stacked meteors one-shot.
- Face him away from the group and block the hammer slam.
- Range-taunt the Flame Atronachs he summons, or let DPS kill them. Watch for their fire on the floor.
- A huge fire behemoth with a hammer.
More detail
Buff Purgator's Accession: +300 Weapon and Spell Damage. His Guardian Stone summons him for 1 minute; your attacks then add fire damage.
- The exact trapdoor and crystal locations for all three guardians. Deltia's guide shows them only in map images, and UESP only quotes Vitellia ('light the braziers by the orange guardian stone').
Scorion Broodlord
Boss- Excruciating Expectoration: a red beam pulls one player in and pins them. Interrupt the boss or they die.
- Agonymium Stone: the boss vanishes up a portal, lands elsewhere and summons a stone that shields him. Kill the stone first.
- Don't leave the arena. It pulls everyone back in and hits hard.
- Keep him facing away. Turmoil is a poison cone he can sweep around.
- Block Crush (heavy). Non-tanks dodge it.
- Taunt the Xivilai adds and stack them on the boss (or on the stone).
- Priority: stone, then adds, then boss. Interrupt the Xivilai casters' channels.
- A curse/DoT hits the group hard and can't be cleansed. Keep HoTs up.
- Stone: a glowing crystal the boss drains while a shield grows on him.
- Torrent of Turmoil: red circles spiralling out from under him in all directions. Step between them.
- Mid-fight he pulls everyone in with a slow and channels a big AoE. Run out before it pops.
Activate: Banner before the boss (veteran).
- More HP, and adds come more often.
- Waves of Bone Colossi and daedroth join. Taunt them, face them away, and kill them before the boss. The daedroth breathes fire; colossi left alive cast fire bursts under players.
More detail
Very hard on melee. If you killed the Purgator, its Guardian Stone in the corner can resurrect allies.
- The Bone Colossus and daedroth adds on HM come from Xynode only. Deltia just says 'more frequent adds'.
Undertaker
Secret bossHow to spawn: Second guardian. Same steps as the Purgator: braziers to its trapdoor, crystals together, portal, light the braziers, touch the stone.
- Soul Cage: lich crystals rise around him, then explode. Stay at range or block when they pop.
Easy fight. Hold him still and stay out of the red circles.
- Kill the Forgotten Deadeye archers as they spawn (more come at lower health).
- A lich. Undying Storm: he rises with arms spread over a huge growing red circle. Get out.
More detail
Buff Undertaker's Accession: +200 Magicka and Stamina Recovery. His stone summons him; your attacks then siphon health.
Cyronin Artellian
Boss- Dread Surge: red waves sweep the room. Martus puts up a shield wall; take the boss there and shelter behind it.
- Soulstorm: he raises his staff with a red beam and fires big red skulls at players. If you glow red, dodge-roll each skull. A hit is a one-shot.
- Heavy (Staff Strike): long wind-up. Tank blocks it; it one-shots anyone else.
- Face him away. The heavy is followed by a lightning bolt on its target. Move off it.
- Hold the two Storm Atronachs on the boss. They come back after a while if killed.
- Boltwyrms: if one is tethered to you, kill it. Tethered players take more damage and get snared.
- Interrupt the atronachs' channels. AoE the small red Restless Dead skeletons.
- Waves: thick red energy rolling across the floor from a crystal on the ceiling.
- Skull phase: a red beam rises from the boss; targets glow red.
Activate: Banner before the boss (veteran). You must have killed the Scorion Broodlord on HM first.
- More HP.
- Two players get a lightning debuff that drops a damaging ground AoE. Run out of the group to drop it.
More detail
A very mobile fight because of the waves. Don't forget your guardian stones if you have them.
- Xynode describes the HM debuff as lightning on two players; Deltia as a debuff that leaves a lethal ground effect. Likely the same mechanic.
Grim Warden
Secret bossHow to spawn: Third guardian. Same steps as the others: braziers to its trapdoor, crystals together, portal, light the braziers, touch the stone.
- Symphony of Blades (spin): don't face-tank it. Even the tank takes % health chunks. Move left or right while holding taunt until it stops.
- Block the heavy and the blue beam. Drag the boss onto adds while dodging spins.
- Kill the Grim Defender adds. Too many alive and the boss goes invulnerable.
- Raging Storm: if a windstorm targets you, kite it away. It can be interrupted. The boss is invulnerable while the storm is over him.
- A mournful aegis spinning blades around itself. A blue energy beam on the tank.
More detail
Buff Grim Warden's Accession: +2000 Max Health. Its stone summons it; your attacks then generate ultimate and reduce damage taken.
Magma Incarnate
Final boss- Unstable Blitz: a tracking red rectangle on up to 3 players. Dodge after about 3 seconds, and don't let rectangles overlap. Getting hit leaves a fire DoT that can't be cleansed.
- Fire tornadoes (Inferno) kill most players in 1–2 ticks. Stay out.
- Consume (around 65% and 35%): he shields himself. Run to the portal on the north side (opposite the entrance) and kill the Agonymium Stone inside, fast.
- Unstable Pulse: the machine charges a huge red circle over half the room. Get out, or block/dodge as it pops.
- Hold him in the middle. Block the heavy (Frenzy), the third swing hits hardest.
- Channel circle: when he plants his swords and crouches in a yellow/orange circle, stand in it and block. If nobody does, it hits the whole group.
- Kill the Scamps (waves of 4) before the boss.
- In the portal, only kill the stone (a Scorion Collector feeds on it). Ignore the other adds.
- Heavy damage while the group runs to the portal. Big heals on DPS when blitz lands.
- A big Ruinach with many blades. Blitz: tracking red rectangles from him to players.
- Portal rooms vary: lava (pulsing fire under you, step away until it drops), frost (spinning AoE with one gap), big boom (block or dodge), or rotating flamethrowers.
- If the stone isn't killed in time, the boss gets buffed and immune for a while. Not a wipe, just slower.
Activate: Banner before the boss (veteran). You must have killed the Scorion Broodlord and Cyronin on HM first.
- A big spider (Spider Matriarch) comes out after each portal. Tank grabs it, everyone kills it first.
- Blitz leaves a fire pool where it lands. Aim yours away from the center.
- Eternal Flames: a ring of fire tornadoes keeps rotating around the room with one small gap. Hug the center.
More detail
After the first portal, he follows a big pulse with a wall of spinning fire tornadoes that has one gap. Holding him in the middle keeps you on the safe line. Roaming tornadoes stay for the rest of the fight.
- Tornado wall: UESP and Deltia list it as HM only. Xynode describes it after the first portal without saying HM.
- Channel circle (tank stands in it): Xynode lists it on veteran; Deltia lists it as HM only.
- Portal thresholds: UESP says 65% / 35%, Deltia 70% / 35%, Xynode '60–65% and 30–35%'.