I just can't beat this last level

[Your New Best Friend]

I could use some help. I had heard using poison you could beat the last boss, but no, poison does nothing to it. It's got a billion trillion armor. You can spend minutes and waves fighting it's fangs, but that just gives it double damage for a few seconds. When it's got a billion trillion armor, double 1 is just 2. I'm fairly certain I'm overleveled as heck for this. Can anyone give some hints for beating this godawful last boss?!

[nray]

Poison is for killing the fangs and killing a fang gives it a non stacking (killing multiple fangs doesnt boost it further) 100x damage multiplier.

First extra hint: Bolt shots bypass armor so enhance your strongest gem with bolt while boss is debuffed from a killed fang

Second extra hint: strongest gem should be a crit gem as crit+100x damage+armor bypass=lots of damage

[Your New Best Friend]

Alright, bolt once a fang is down. Jeez, what a mission. I'll try again.

[The Chronic Cleric]

I also put up a line of mana leech gems on the orb approach to gain a large amount of mana to help press forward. I spent a bunch of time getting distracted by the spires but you can really just push down, I had a poison-crit gem for killing fangs and then focusing on the gatekeeper when the buff was up and I had bolt ready. It ramps up if you keep upgrading and pressing in.