Underworld Crypt: 1 Vs Endless Mobs?

So I started the Underworld Crypt for the first time just a little while ago, and I progressed through it swiftly and easily. (I kinda forgot about it, and I'm level 39 now xD) And so I made it to the boss fight, and I entered the boss room (I sat in a black tube for a while after I clicked the button) and everything seemed to go fine. I got the usual "How dare you enter my arena >:(" quote from the boss, and then a bunch of mobs started spawning! (I mean that made sense, considering I'm supposed to be fighting an undead army right?)

Well that was all fine and dandy, but after about five minutes of killing I started getting curious...tried to cross the white particle line...nope, General WhatHisName tells me to keep control of the battlefield. So I follow his command and kill mobs for a solid 10 more minutes. Still nothing? No chat messages, no prompts to get me to do anything, the mobs aren't dropping anything interesting...whats the deal? Plus, the way things were progressing, I feel like I was supposed to be followed in there by an army of aimbottin' NPCs of some sort?

So was I right to think that it glitched out? Or that its bugged? Or am I just not patient enough, and I need to control the damn battlefield like I was told to do? xD

Thanks!

 

If you step on the plates near the enterance of the room it summons mobs to kill and hurt the boss. It's basically tower defense

Or just smoke bomb him

 

Ohhhhhh...well that kinda makes sense...gal darnit...xD thanks for the speedy reply!

 

No problem =D

 

SUMMON YOUR ARMY WITH THE PRESSURE PLATES.
THEY FIGHT, AND DIE FOR YOUR HONOR.
WITH YOU ON THEIR SIDE, THEY WILL SLAY THOU ENEMY.

 

Well, right after the gameplay update it was sometimes broken, meaning that your army couldn't spawn.

 

That also happened to me but you could just smoke-bomb, ice-snake, meteor or shoot the boss with an archer/hunter.