Leotheras the Blind

He’s the 3rd boss in Serpentshrine Cavern with 3,700,000 hit points and 221 gold wealth.
Abilities
Human Form

Whirlwind: Leotheras will spin around the room in a fashion similar to the Battleguard Sartura encounter in Ahn’Qiraj. This ability deals direct damage and leaves a bleed dot. Leotheras resets all aggro after the whirlwind.

Demon Form

Insidious Whisper: Debuff that summons […]

The Lurker

The Lurker is the 2nd boss in Serpentshrine Cavern, has 4,900k hit points and hits tanks for 4k-5k dmg. You don’t have to kill Hydross the Unstable to reach The Lurker. Most guilds manage to kill Lurker first.
 Abilities

Whirl: Every 15-30 seconds, Lurker whirls all players in melee range for 3000-4000 damage while knocking them back. […]