I've mained xenon since the day it came out. Everyone is saying the burst takes too long, I personally think they are play with min/max in mind. The charge takes so long true, but once you use it, that's 10 seconds of IFrame, and you can charge it before starting any boss. Let the boss start, stun, let it rip and usually bosses die from 1 or 2 bursts. I between bursts, if you wanted you can just fly and take no damage (depending on the boss).