Beltyn's Burning Blood.

[VanillaPudding]

You infuse a living creature's blood with a hot, corrosive mxture, dealing 1d8 acid and 1d8 fire daamge each round. Each round the target may attempt a fortitude save to negate the damage  - for that round -. On any round which the creature fails it's save, it is slowed.

This is the spell description, however, whenever a save is made the spell fades off like combust would. In it's current form it seems to be rather weak for it's level. Any chance of getting the save to not remove the spell completely?