Eternal dungeon teams

[Yup]

Darkstar Clairvoyant... I used...

Van Helsing, BHE, Cyborg, Crusader Ed --
-- Note that Dark Clair is pretty immune to magic or physical damage. You need a true damage dealer to hurt her.
I used Van Helsing and his Mark ability to throw marks on her.. which will damage her. Alchemist is a 1-hit kill much of the time with Van Helsing.
Crusader Ed also worked pretty well.
(Didn't have BHE at the time)

Clairvoyant (Destiny/Warp)
-- she'll remove that Endure buff and tick the achievement

Raven Witch (Labyrinth/Cosmic Echo)
-- Perfect corruption keeps Endure from appearing
she does true damage which is the only way to hurt Dark Clair, Echo Cosmic can take her out quickly if Endure isn't there.

Killer Prime (Warlord/Tranquility/Sustaining)
-- Mostly for his buff removal and Permadeath passive to keep the others from being revived and to kill them.
And the Sustaining talismans keep everyone healthy.

Had to do it manually so as to remove Endure and THEN kill Dark Clair.

I always killed Alchemist first so he wouldn't Fury and grant Soul Protect to anyone or heal everyone.