thought i'd contribute, it's been loooooooonnng overdue
the spot is Fjorn's Anvil, the circled one farrrrrr east in storm peaks. coords (77.63).
mob is Seething Revenant - NPC - World of Warcraft
they drop crystallized fire and relics of ulduar, which on my server go for ~24g per eternal fire and 3g per relic. i made over 2k gold in 2 days farming this spot for my epic flyer. i was not farming all day, just from 8AM-1PM both days. so say your server has a high demand of relics and eternal fires, you could could be making bank with some effort. fast respawn and a good drop rate.
another spot is a bit north of K3 that is also circle, at 43.70 for coords , is the Exhausted Vrykul - NPC - World of Warcraft and Captive Vrykul - NPC - World of Warcraft with a wopping 48% drop rate of relics of ulduar! i only go here if my preferred farming spot is taken
in addition to the relics/crystallized fire they guys drop, greens and grays aka vendor trash also drop. hope this helps everyone, good luck farming.