Mordy grim would make it stronger, focus and fire magic.
Fire gear, if u can make firebolt 50 without dl gloves, wear beastboen gloves, extra 300 dmg, the rest obsidian
Fire Magic/Focus on other stuff, and mordy firebolt brace if there is any
Ofc thats if u just want to have highest firebolt, not using ur normal build and gear.
I have shadow Mordy grim with focus and fire magic.
I have 50 fire bolt without gloves
I have royal mordy brace
I don't think anything above 7500, let alone close to 8000 would be possible...
Well a stronger grim and brace would help, and did u try a sunfire firebolt charm? A royal one would add 150 direct dmg, which idk if it tops any other dmg bonus from charm available, if u can borrow an imperial or godly, even better.
Rings for foc (75 foc, 50 foc, whatever else u got), dl offhand, any brace that would help (i cant come up if theres any better one than foc brace, as high as u can get, 100-100 is hard to find so u could try and borrow 90-90 with foc)
and ofc rebirthing for full foc.
Thats for highest skill hit, ofc u would prob die on normal fight with no vit and only foc/firebolt gear, but who knows how the dps will be (with that cooldown, and such high dmg, firebolt could prob nuke)