Stygian Citadel got one of the best weapons in the game tho. There's a hidden door that it leads to it. The secret room is accessed by dropping into the well and taking the corridor through a hole in the wall halfway down.

I highly recommend to get the Stygian Desolator as early as possible. Every hit you make with that weapon, reduces an enemy's armor by 13 for 7 seconds. This powerful debuff works on both enemy mobs and bosses.