One of my favorite skills in PoE is fireball, and I really wanted to build a hit based version this league. My initial idea was to use Legacy of Fury boots, Flamesight, and Rolling Flames to get 100% scorch chance, and Fury of Nature forbidden jewels (prolif) but it ended up being better DPS and clear just using elemental focus. The build is decently fast and has huge aoe clear which makes it really fun to play. I've done all the pinnacle bosses, but I would say it's pretty bad at bossing since optimal DPS is while standing still.

PoB: https://pastebin.com/aKUkMUbM

Better PoB without need for ballista totem: https://pastebin.com/g7ig3YuV