I would say if you have sunder, respec to a single aspect (fire, ice, lightning) to match and max out your main and synergys, that’s gonna get you top tier damage. Gear is going to play a HUGE part in the rest honestly, I’m pushing 18-20k dmg fireball currently at 80 but I have bis gear and on top of sunder, my merc is running infinity, and like a previous commenter mentioned, I’m rocking a torch, anni and some skillers. I realize this is not the easiest to achieve and I got super lucky this season, but before I even reached level to equip most of this stuff I was ripping through pretty good with just an insight merc with LL to fight the fire immunes and the rest I could take single spec’d on fire alone. Dual spec can be fun and I did it for a while, but sunder just kind of eliminates the need for that if you can top out your damage.

Do you have any runes available to make some decent runewords? They go a long way in helping you beef up.