Lord Nagafen, along with Lady Vox, Phinigel Autropos, and the Avatar of Fear, is one of EverQuest's original four raid bosses.
In Nagafen's Lair: Warrior; hits for a max 250; has 32,000 hps; summons. Fire and magic resists (to avoid his AEs) are key in defeating Nagafen. Note that players over Level 52 get banished from the zone if they get onto Nagafen's hate list.
In Nagafen's Lair (Level 100 Revamp): See this quest entry for raid details and loot.