Since the event is going on and plenty of folks are doing the Orsinium boss dailies, I thought I would share a couple quick helpful hints for Snow and Steam. Nyzchaleft hits very light with his normal attacks, so if you have decent mitigation and self healing, you can easily tank those attacks if there is no proper tank available. Even his heavy windup strikes cause no significant damage, nor do they knockback like similar type dungeon bosses do.
The only situations you have to worry about are when the boss spins and drops circular AOEs on the ground and when it stands with its arms bent and shoots steam blasts to the front and back or sides. For the AOE hazard, get out of the circle directly around the boss as quickly as possible, due to very high damage and a hit stun, and watch your step as each of the smaller ones spawn nearby. Do a little dance to avoid them. You can cast defensive skills and drop your own AOE to nuke the adds that spawn.
For the steam vent hazard, simply move to one of the very edges right outside of the cone attack. Once you are in that safe zone, the steam that spawns in the alternate directions will not hit you, so you can stand there the entire time and attack the boss. Basically at 45 degree angles from whichever way the boss faces. If you are nervous about your positioning, you can also move a little bit to one side or the other as the spray alternates, so you don’t stand in the hazard too long.
I see a lot of people die to these mechanics, but if you pay attention, you should find this fight pretty easy.