Trial of the Champion

Stage 1 -Random Draw-

Marshal Jacob Alerius - Human Warrior
Colosos - Draenei Shaman (Healer)
Jaelyne Evensong - Night Elf Hunter
Lana Stouthammer - Dwarf Rogue
Ambrose Boltspark - Gnome Mage

You will get 3 of them with 3 each champions from their respective factions.

Stage 2 -Random Draw-
One of the following will come out with 3 groups of 3 NPCs each.
Group composition
One Priestess - Spawns a Lightwell that will heal the group they are in.
One Monk - Will put up a bubble on Heroic that will make them immune to all attacks (can be Shatter Thrown) when they are at 1%
One Lightwielder - Basic Fighter.

Boss
Eadric the Pure:

Has a move (Radiance) that you will need to turn your back to while fighting or you will be blinded for approximately 3 seconds.
Also will stun one party member and throw Hammer of the Righteous. It is occasionally caught by the player and can be thrown back. Has an achievement associated with it [The Faceroller]

Argent Confessor Paletress:

Will put up a shield for the duration of the fight and summon a boss from the past ranging from Hogger to Vezax. (I have done this twice when she comes out and have fought Onyxia and Heigan)
The shield has a similar effect to a Discipline Priests Reflective shield.

Stage 3

The Black Knight:
Phase 1
Will kill the Sunreaver Fight Master and turn him into a ghoul for fight (CCable) and will explode when down to about 15-20%. Burn him down.
Phase 2
Summons an Army of the Dead. Will follow same mechanic as the ghoul in Phase 1
Phase 3
He is a ghost that will mark one person with "Marked for Death (Debuff that increases damage taken by 200%[Heroic])." Continually casts a shadow spell that also increases dmg from shadow spells.

Every drop in this 5 man instance will drop Epic quality items.

For anyone interested: it is decided for each run whether Eadric or Paletress spawns.

Of course there is a daily ID on the heroic version.