Entombed Sentinels — Guide to a boss of The Venomous Abyss

Two-target fight: two golems, Breath of Ula'tek (green) and Blood of Ula'tek (red), with separate health pools. Single-phase, with a recurring intermission.

The constraint that shapes positioning is distance, and the number is 40 yards. If the two golems are within that range of each other they reduce damage taken by 99%, so they must be tanked at opposite ends of the arena with comfortable margin. Forty yards is also the radius within which each golem applies a stacking DoT to players, so the raid splits into two fixed groups, one per side, that never mix.

Each golem has its own set of mechanics, all manageable individually. The green one spawns orbs that return after a few seconds, a slime that deals constant raid damage while alive, and toxic droplets that erupt if not stepped on within 12 seconds. The red one applies a dispellable DoT, a group soak, and a debuff that leaves a pool on expiry, larger the more applications the player has accumulated.

The intermission, Vitriolic Stasis, triggers when the golems reach 100 energy: first at around 45 seconds, then every minute and a half. For 30 seconds both sit at 99% reduction, so damage is irrelevant and the raid solves a minigame: each player receives a number of charges and must pair with someone so the total is exactly 4, or take heavy burst damage. At the same time the more damaged golem is healed up to match the other's percentage, so damage concentrated on a single target is refunded and both bars have to be kept level for the whole pull.

Anyone who played Cauldron of Carnage or Amalgamation Chamber will recognise the structure.

TL;DR

What to do

Everyone

Always: stay on your side. Each golem applies its mark to anyone within 40 yards, so never cross the room.
Always: step on the Toxic Droplets within 12 seconds of them appearing.
Always: join the Unstable Miasma soak and drop the resulting pools in the agreed direction.
Intermission: pair up so your Helical Toxins applications sum to exactly 4. You have 30 seconds.
Mythic: players contaminated with Shifting Protovenom only touch each other.

Tank

Always: keep the two golems beyond 40 yards from each other. Inside that range the 99% reduction kicks in.
Always: move the red golem along an agreed direction because of the pools.
End of intermission: swap targets.
Tank swap on Empowering Slam (green) and Bloodvenom Injection (red).

Healer

Always: dispel Blighted Blood.
Proximity marks are constant stacking DoTs: the damage is attrition, not spikes.

DPS

Always: kill the Venom Coagulation immediately, as it pumps raid damage every 3 seconds.
Always: keep the two golems' health aligned (see Vitriolic Stasis).
Intermission: the golems sit at 99% reduction, so damage is irrelevant. The focus is solving the charge minigame: check your number, find your partner, add up to 4.

What can kill you

Ability	When	How to avoid it
Cultivated Burst	Intermission	Complete the minigame: the toxin must reach 4 applications
Protovenom Eruption	Base cycle, Mythic only	Never touch an uncontaminated player while carrying Protovenom
Blighted Blood	Base cycle, red golem	Fast dispel
Blood Venom	Base cycle, red golem	Drop pools in an orderly line, not scattered
Living Venom	Base cycle, green golem	The orbs return after 4 seconds: stay off the return path
Mighty Thud knockback	Base cycle	Don't handle the mechanic near the edge

What wipes the raid

Mistake	When	Consequence
Toxic Droplets not stepped on	Base cycle	Each droplet erupts into Noxious Blast on the whole raid
Venom Coagulation ignored	Base cycle	Contaminate every 3 seconds on everyone
Minigame failed en masse	Intermission	Simultaneous Cultivated Burst across most of the raid
Golems too close together	Always	Ula'tek's Dominance: −99% damage taken, the fight stalls
Golem health imbalanced	Every intermission	The Stasis heals the lower one up to match the other: excess damage is refunded

Timeline

Point	What happens
Pull	Raid splits: green group and red group, golems 40+ yards apart
Base cycle	Toxic Droplets, Living Venom, Venom Coagulation (green) · Unstable Miasma, Blighted Blood, Blood Venom (red) · Shifting Protovenom on Mythic
~0:45	First Vitriolic Stasis, 30 seconds: the raid solves the Helical Toxins minigame, then tank swap
Then every ~1:30	Subsequent Vitriolic Stasis, identical pattern

The trigger is the golems reaching 100 energy.

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Detail

The two golems

Breath of Ula'tek, the green golem. Animates venom: orbs, slimes, toxic droplets. Predominantly Nature damage.
Blood of Ula'tek, the red golem. Infects players and floods the ground with pools. Predominantly Shadow damage.

The distance rule

Ula'tek's Dominance: if the two Sentinels are within 40 yards of each other, they reduce damage taken by 99%.

So tank them beyond 40 yards, in opposite positions, with margin since the red golem has to be moved constantly because of the pools and the green one follows.

A note on the numbers: PTR builds listed a 25-yard threshold, while the current value is 40 — the same radius as the proximity marks. Guides quoting 25 yards are referring to the older build.

Proximity marks

Each golem applies a stacking debuff every 5 seconds to anyone within 40 yards:

Mark of Acid — Nature DoT, from the Breath.
Mark of Blood — Shadow DoT, from the Blood.

This is what forces the raid split. Anyone crossing the room picks up both marks.

Breath of Ula'tek — green golem

Living Venom (Heroic/Mythic) — slime orbs that return to the golem after 4 seconds, damaging anyone on the path.
Venom Coagulation — a living slime that, while alive, inflicts Contaminate on the whole raid every 3 seconds. Priority kill.
Toxic Droplets — toxic droplets that erupt after 12 seconds into Noxious Blast. Neutralised by walking over them at negligible personal cost. In PTR testing they appeared on both sides of the room, not only on the green side.
Empowering Slam — tank hit. Striking the same target consecutively grants the golem +10% physical damage, held until it strikes a different tank.

Blood of Ula'tek — red golem

Blood Venom (Heroic/Mythic) — on debuff expiry the player leaves a toxic pool. The more applications accumulated, the larger the pool.
Blighted Blood — heavy DoT, dispellable.
Unstable Miasma — marks a player; after 8 seconds it erupts, split among everyone within 7.5 yards. Group soak. The impact spreads Clinging Murk.
Bloodvenom Injection — injects the current tank: immediate damage plus a 40-second stacking DoT. Stacks build while the tank keeps being hit, and on expiry generate a very large pool that must be dropped against the edge.

In PTR testing the only critical moment came from here: the large pool was dropped in an awkward spot instead of against the wall.

Intermission — Vitriolic Stasis

First occurrence at ~0:45, then every ~1:30. Both Sentinels run to the center and channel for 30 seconds:

they take −99% damage;
the more damaged golem is healed up to match the other's percentage;
the whole raid receives Helical Toxins.

Because the Stasis realigns health upward, any damage concentrated on a single target is refunded. Both bars must be kept level throughout; the raid leader monitors the gap and calls swaps before 100 energy. There is an achievement tied to this: Is Venom Stasis A Joke To You?

The Helical Toxins minigame

Each player receives a number of applications, shown as orbs above the head, some green and some red. The total is always 4, so by convention only the green ones are counted.

Two players who touch combine their applications. At exactly 4 the toxin is neutralised.

You have	You need
3 green	1 green
2 green	2 green
1 green	3 green

If the debuff expires without reaching 4, it erupts into Cultivated Burst: heavy damage on the host plus a one-minute DoT.

Thirty seconds is plenty but requires everyone to check overhead and move immediately. Calling out your number in voice chat is the fastest way to resolve it.

Afterwards the tanks swap targets.

Mythic addition — Vashnik the Malignant

Vashnik periodically appears and contaminates several players with Shifting Protovenom, visible as a red circle around the character.

Contaminated touching another contaminated: the venoms neutralise each other.
Contaminated touching a clean player: Protovenom Eruption, damage within 10 yards and knockback. Both die.

The raid pre-spreads, then only the marked players approach each other. Anyone without the circle stays put.