Your Wiz is really good man. Not MUCH to change or get really for mega firey fire build.
Get a Unity ring to replace the yellow you have. PRefer get a socket in that for a leg gem.
Consider Tal Rasha amu and belt, with RoRG you have a 3 set bonus there waiting including 5% fire dmg on the 2 set of that. Socket in Tal Rash amu also for leg gem.
I'd go 23% life amu in your helm.
Your RoRG as an absolute belter by the way! Jammy bugger, it's almost perfection.
Blizzard with apocolypse rune is better than energy twister.
Mirror Image with duplicate rune instead of slow time. Your 4 mirror images spam mobs with black holes which proc your strongmans and you'll also see 3/4 hydra's now and again!
Elemental Exposure, drop that. You are only dishing out big fire damage so that's not worth it. Use the fire skill one. Conflagration gives good fire boost and also consider taking unstable anomoly this gives you a life line in higher level grift which you will need along with your revive from 6 set FB bonus. 2 free deaths haha.
Your Wiz is T6/Grift 28 solo level ALMOST I would say.
Serpent Sparker much better than mine, a shame that didn't roll fire dmg but still it is nice.