The hardest thing about Nezarec, at least from my time fighting him was that 99% of the wipes was because someone did something stupid or wasn't paying attention. However, there are known issues that will happen with the game if you remain in an instance for too long. One of my teams got stuck on Nezzy for about 3.5 hrs and by that time we had a bunch of bugs happening such as, The Rally flag wouldn't give any ability energy. The auras the runners had to grab would despawn periodically. Nezarec wouldn't jump down from his platform no matter how many times he was shot in the chest and his shoulders couldn't be broken. Out score counter defaulted to x0 instead of x3. Nezarec never got "stunned" by the beam of light to start DPS and he was immune the entire time. The Light and Dark Colossus shields wouldn't take any damage whatsoever from the buff carries. Enemies wouldn't spawn when the encounter started but then they'd spawn all at once in huge cluster in the middle of the map. (That one was crazy as hell) Now, normally you could just go to orbit and reload to encounter to fix these issues but given how the Pantheon score works, you can't really do that for the final boss. So... Gotta tough it out :)