Damage everything within a 10 ft. radius of a point within 300 ft.
Intensify: You may add +5 ft. to the radius of this spell per boost from Intensify.
Friendly Fire:
You can try a DC 15 test of Spellcraft to exclude a target from being affected by your spell.

All creatures in the area get a health (reflex*) save.

Fail:
The creature takes 1d6 elemental damage.
Intensify: +1d6 elemental damage per boost from Intensify.

Pass:
The creature takes half as much damage.

Suggested Backfire: The spell blows up in your face. You take the full damage unless you pass a health save for half damage. Noone else is affected.

*If you cast this spell with the poison or dark element, the save against this spell is a health save.
Otherwise the save against this spell is a health (reflex) save.
Certain abilities interact with health (reflex) saves.

You overcharge your Arcane Ball spell.
Targets have disadvantage on their saves against Arcane Ball.
Add up to 10 ft. to the radius of your Arcane Ball.