Bloodroot Forge

Lunge

All: He rears up and strikes in a frontal cone for very heavy damage. The tank keeps him faced away from the group; avoid the cone entirely where possible.

Nirnblooded Guar and Senche

Tank: Waves spawn at roughly 75%, 50% and 25% health. Root and taunt them alongside the boss.

Dps: Kill the adds quickly to simplify the fight; their heavy attacks are dangerous if they are left alive.

Strangler

Dps: A Strangler spawns and coats the arena in poison. Top priority; kill it quickly.

Scorch of Summer and Chill of Winter

All: She alternates a flame bolt, which applies weakness to frost, and a frost wave, which roots and applies weakness to fire. Each makes the other's follow-up hit harder, so avoid both where you can.

Wave of Earth

All: A rock barrage in a frontal cone that stuns anyone hit. Stay out of it.

Nature's Preservation

All: At roughly 75%, 50% and 25% health she shields herself with three trees and becomes immune. Anyone inside or touching the circle is stunned and thrown out, so back away before she reaches the threshold. Adds inside the shield are also invulnerable; the tank drags them out for the group to kill. Wait out the shield while handling adds.

Nirnblooded Bears, Guars and Senches

Dps: Each Nature's Preservation phase also spawns a growing wave of animals. Bears and Stranglers are the priority kills.

Scorched Ground

All: Being hit by his ranged Flare leaves a fire damage-over-time circle under you. Step out of it.

Fire Bloom

All: He roots the whole group and sends fire lines along the ground toward you. Dodge roll to break the root, then step around the lines.

Stone Atronach

Dps: He periodically wakes a Stone Atronach. Its damage increases the longer it lives, so kill it quickly.

Execute Enrage

All: Below roughly 20% he wakes every Stone Atronach in the room at once. Save ultimates for this and finish him immediately.

Inflamed Earth

Tank: His basic melee leaves a fire damage-over-time circle under you. Keep moving out of your own puddles.

Cleave and Wake of Fire

All: His arcing cleave also releases three flame lines outward in the direction he faces. Nobody but the tank stands in front of him.

Mantle Breaker

Tank: A charged heavy attack; block it. It summons a small volcano at the impact point that fires lava balls at the group. Stand on top of the volcano and block to seal it. The damage taken while sealing it is high, but far better than letting it fire freely.

Scorched Earth

All: He throws his weapon and a large expanding circle covers the whole island; it is lethal on Veteran. Jump onto one of the surrounding rocks to escape it. Only one player per rock: extra weight makes a rock vanish faster and drops everyone on it into the lava. Falling into the Molten Nirncrux itself applies a severe damage-over-time effect.

Fire Shalk

Dps: Fire Shalks spawn throughout. Kill them quickly to keep the room manageable.

Uppercut

Tank: A knockback-and-stun melee attack. Block it to knock Gherig off balance instead.

Cleave Stance

All: He enrages briefly and uses only strong frontal cleaves. Stay out of the cone.

Fire Chain and Pyrocasm

Tank: He pulls you in with a chain, then bursts flame around himself, knocking back and stunning. Be ready to reposition afterward.

Attendant of Blood: healing

Dps: The Attendant of Blood continually heals the trio with Focused Healing, a Quenching Blood puddle, and Rite of Passage. Interrupt her on sight, and pull enemies out of her Quenching Blood puddle so it stops healing them.

Attendant of Flame: Burnt Offering

Dps: The Attendant of Flame chains players to the ground with a growing effect beneath them. Interrupt her quickly to free them before it triggers, or they take severe fire damage.

Stack and kill order

All: The tank holds all three close together. Kill Bullblood first, then the two Attendants, interrupting both constantly along the way. Watch for spreading lava pools from the centre of the arena.

Anvil Cracker

Tank: A charged heavy attack for very heavy damage. Block it, or dodge it if you do not have aggro.

Stonefall (Groundshaker)

All: At roughly 80% health and below he channels a stomp and becomes immune while rocks rain down. Move between the two safe rally points, the edge of the arena and back, so the healer is not chasing players running in circles. On Normal, the fire brazier can stun him during this channel and the blood brazier clears the lava fields; neither is available on Hard Mode.

Falling Debris

All: Rocks fall from the ceiling throughout the fight, more heavily during Stonefall. Keep moving; a hit knocks you down.

Drown in Flame

All: Lava balls land and pool at random spots, dealing heavy fire damage to anyone nearby. Face the group toward a wall so the shots land predictably rather than scattering, and use the Flameslake Cauldron synergy to clear a pool where available, on Normal only.

Summon Clones

Tank: At 75% and 50% health he splits off a medium and then a small clone, all sharing one health bar. Hold aggro on everything; it becomes demanding quickly.

Dps: All clones share the boss's abilities. Kill them smallest, then medium, then original. Smaller clones die faster, and the longer any clone survives, the more lava spreads, until it can cover the whole arena.

No Braziers (Hard Mode)

All: The stun brazier and the lava-clearing brazier are both disabled on Hard Mode. You must out-damage the lava spread and kill the boss and its clones before the arena fills, with no help from the synergies.