Build question with mythics I got

Hi, I got heir of perdition (unfortunately with GA on movement speed) and ring of Starless Skies

I would like to do a fireball build, but idk what would be the best

• I need some help with picking pants and boots, for now I'm wearing tribults will or whatever it's called and some low unique ones with freezing the ground idk what it's called either I have illuminators gloves which is cool and endless rage staff with 3 GAs