Guntharius

Hellfire Citadel

Here is a quote from the World of Warcraft web site concerning loot iLvl:

In Hellfire Citadel, players will be able to earn items ranging in power from item level 675–685 in Raid Finder up to item level 735 in Mythic difficulty.

Normal & Heroic
Hellbreach
Hellfire Assault FATBOSS (6:42) Two Minute Tips (2:36) TL;DR (2:07)
Iron Reaver FATBOSS (5:40) Two Minute Tips (2:36) TL;DR (2:00)
Kormrok FATBOSS (7:39) Two Minute Tips (2:31) TL;DR (1:51)
Halls of Blood
Hellfire High Council FATBOSS (8:10) Two Minute Tips (2:55) TL;DR (2:20)
Kilrogg Deadeye FATBOSS (7:51) Two Minute Tips (2:51) TL;DR (2:24)
Gorefiend FATBOSS (8:12) Two Minute Tips (2:43) TL;DR (2:22)
Bastion of Shadows
Shadow-Lord Iskar FATBOSS (8:17) Two Minute Tips (2:48) TL;DR (2:27)
Fel Lord Zakuun FATBOSS (9:39) Two Minute Tips (3:02) TL;DR (1:58)
Xhul'horac FATBOSS (11:01) Two Minute Tips (2:47) TL;DR (2:19)
Destructor's Rise
Socrethar the Eternal FATBOSS (8:40) Two Minute Tips (3:16) TL;DR (2:06)
Tyrant Velhari FATBOSS (11:58) Two Minute Tips (2:52) TL;DR (2:20)
Mannoroth FATBOSS (12:55) Two Minute Tips (2:45) TL;DR (3:09)
The Black Gate
Archimonde FATBOSS (13:26) Two Minute Tips (3:33) TL;DR (4:14)