Starbuck_II
Explorer
I would think that any round a person is on fire, it's reasonable to take a move action to put yourself out. That's it. No save.
Note that magic cloaks get far better saves than non-magic equipment.
Personally, I would change this to 1d6 instead of 1d8. Note that as a single target spell, it's still subject to the caps in the DMG, which I believe make it 10d6 (10d8 in the original) max damage.
But now you might as well use Scorchin Ray: a range touch that deals Max 12d6.
I believe they up'd danmage to account for melee touch is dangerous.