Haros

Boss
[1/4] Haros: Come on, we've nearly broken through to Saint's Row! Detonate it already! [2/4] Haros: Their east side is undefended. We will overrun the town! Charon will regret banishing us all! [3/4] Haros: WHAT! A human?! How did they find out about our plans?! [4/4] Haros: Soldiers! Destroy the interloper! We cannot let them keep us from our goal!

The boss of the Rotten Passage is the level 30 Haros. Haros has a total of 7000 health, and has a Heal AI - he rarely attacks you directly, and follows his minions.

Minions
There are four other types of mobs in the arena besides Haros. They are the Banished Legion Bolter, Router, Trooper, and Shanker. They are all level 25, and have varying attack forms, providing the bulk of the difficulty of the battle.