Ray D. Tear

You can find his grave in the garrison's graveyard (at least in the alliance one).

Also, he can shapeshift into any HFC boss, explaining why he's the 18th (Ray D. Tear the 18th = 18th raid tier)

Ray D. Tear is a wicked soul that shapeshifts to represent a range of bosses from Tier 18: Hellfire Citadel, each using one of their signature moves. Ray D. Tear transforms into Siegemaster Mar'tak that casts [spell=229013], Kormrok that casts [spell=229022], Gurtogg Bloodboil [spell=229035], Kilrogg Deadeye that casts [spell=229031], Gorefiend that casts [spell=229162], Fel Lord Zakuun that casts [spell=229165], Tyrant Velhari that casts [spell=229039], Xhul'horacthat casts [spell=229042], Mannoroth that casts [spell=229051], and lastly Archimonde that casts [spell=229060].

Avoid [spell=184393] as it one-shots you, use a defensive for [spell=229022] if you can, remember that [spell=229035] applies a bleed and an armor debuff, side step [spell=229031] and [spell=229162], drop [spell=229165] in the corners to have good space to dodge the fel waves, use a defensive, heal or immunity for [spell=229039], move away from [spell=229042], and interrupt [spell=229051].

As palaret last boss required me around 550k dps to kill it before enrage.
You can prepots with arena pots + oldwar/prolonged then again do it 1 min later probably need a drum/bl also
Will be way easier with nighthold stuff tho