Stay in the Light
Tank: She takes almost no damage outside brazier light and deals a heavy damage-over-time effect to anyone standing in the dark. Pull her into the lit area and keep the fight there.
Sithera
Voice of the Spinner
Dps: A channeled explosion that splits into three ground waves. It is easy to see and interrupt, so interrupt it every time.
Giant Spiders
Dps: She summons spiders to harass the group. They cleave down easily.
Brazier Transitions
Tank: At roughly 66% and 33% health she extinguishes the nearest brazier. Move her to the middle brazier at 66%, then to the final one at 30%, keeping the fight lit throughout.
Poison Spits
Tank: Random poison spit attacks. Block them when they land on you.
Khephidaen
Pull of Darkness
All: Standing outside the braziers' light slows you and deals damage over time. Stay lit throughout the fight.
Voice of the Spinner
All: A channeled magical explosion that splits into three ground waves. It deals heavy damage even to tanks; avoid it entirely.
Tide of Darkness
Tank: She swings her staff, releasing projectiles in front of her for very heavy damage. Block it, since the telegraph is clear, and keep her faced away from the group. Dodge rolling also avoids it.
Interruptible Channel
Dps: She teleports near a brazier, often on the opposite side of the room, and channels with red lines radiating from her. Interrupt it, or it knocks everyone hit off their feet.
Brazier Extinguish and Gloom Wraiths
All: About once a minute she extinguishes the room's braziers and summons Gloom Wraiths, each spawning two Swarming Beetles that keep coming while the brazier stays dark. Reach the braziers and use the synergy to relight them, and kill the wraiths.
Votary of Velidreth
Fight in the Middle
Tank: Hold the boss in the middle of the room, never a corner. The middle is safe from the burst effect below; a corner is a death trap, with nowhere to move.
Spider Adds
Dps: Small spiders drop from the ceiling. Kill them quickly before their passive effect accumulates.
Spew Venom
All: Several poison circles land on a player's current position. Do not stand near teammates, or the poison catches more than one player.
Webspinner's Wrath
All: She pulls everyone in front of her inward with webs, then bursts a large effect around herself. Avoid this at all costs; even the tank should be ready to roll out.
Dranos Velador
Never Drop Taunt
Tank: If the taunt drops, his mechanics start landing on random group members instead of you, which is how this fight collapses into repeated wipes. Keep it locked for the whole encounter.
Shades of Dranos (about 66% and about 33%)
All: He becomes invincible and four Shades of Dranos appear. Killing each drops an Essence of Velador; collect all four to return them and stun him briefly, making him vulnerable again. If the boss himself touches a shade it returns automatically, so pulling the boss onto a shade with a grip can shorten this phase. Handle it quickly, as he keeps attacking throughout.
Orb of Spite / Wrath of Mephala
All: The Mephala statue in the centre releases exploding magic orbs, and constant waves instead once he is low. Avoid this at all costs; staying near the edges of the room helps dodge the wave version.
Searing Seal and Pin
All: He teleports to each player and drops a fiery glyph underfoot (Searing Seal), then teleports to one player, usually the tank, and pins them with two Gloom Wraiths. Everyone else interrupts the Wraiths to free the pinned player immediately, who must then block the follow-up heavy attack. A non-tank is likely to die to it even while blocking, so dodge rolling at the swing may help.
Blade Weaver: Teleport Chain
All: He teleports to each of the four players in sequence; block for each. After striking one player he moves to the next, leaving an effect under the one just hit. Step out of it once he moves on.
Velidreth
Hard Mode: Examine the idol on the Altar of Adoration, then burn the webs, to enrage her (Veteran only; achievement: Velidreth's Vengeance). This adds roughly 600,000 health. A group wipe deactivates Hard Mode; burn the webs again to re-enable it.
Flurry
Tank: A small frontal cleave. Block it, but never turn her to face the group while doing so. A DPS or healer caught in it dies quickly.
Melee and Ranged Adds
Dps: Melee adds throw uppercuts; ranged adds need interrupting. Kill the adds first every time, and do not push her too hard while they are up.
Shadow Sense
All: She calls out and climbs to the ceiling, darkening the room and marking each player with a white circle underfoot; stepping off it triggers a damaging spike. When the purple hue fades and the ground trembles, a larger red circle replaces it under each player, and this one must be dodge rolled out of, not merely stood in. Watch the ceiling: her stopping and then starting again is the cue to roll. Rolling too early or too late is instantly lethal.
Devour
All: She pulls in whoever has the most Ultimate charge and drains it entirely. It cannot be avoided, only pre-empted: use your Ultimate as soon as it is ready, or slot the cheapest ones you have.
Draining Orbs
All: Coloured orbs float around the room: red drains Health, blue drains Magicka, green drains Stamina, matching the resource of whoever's Ultimate was just drained. Avoid all of them, especially the red ones once the room fills up below 30% health.
Atronach Spawn (about 66% and about 51%)
Dps: Atronachs spawn at these thresholds and must be focused immediately, ahead of the boss. Each drops a light on the floor. Assign two group members, one per eventual catacombs group, to each pick one up; skipping this makes the next phase very hard to finish.
Catacombs Banishment (about 66% and about 31%)
All: She banishes the group into a maze, split randomly into two pairs, each with one light-holder. Stay close to your partner, as leaving them in the dark snares and eventually kills them. Avoid the dremora and hoarvor adds along the way; group crowd control such as Time Stop helps. Watch for red trap pads, visible only in the light. Find an open doorway back to the middle. On Hard Mode all doors but one start closed, so expect real backtracking. The same door stays open on the second banishment, which means a return trip through whatever adds were left behind the first time.
Resurrection Interrupt
Dps: She fires a fast projectile at anyone attempting to resurrect a teammate. Interrupt her so the projectile misses; she will not try again on that resurrection attempt for a while, so a cancelled fake start can bait the interrupt and clear the way for a real resurrection immediately after.
Execute Phase (about 31% onward)
All: No new mechanics after the second catacombs trip. Stack and focus her down from here; stay alive and focused.
Closed Catacombs Doors (Hard Mode)
All: On Hard Mode, three of the four catacombs doorways are shut when the group is banished. Expect to backtrack through previously cleared territory to find the open one.