OOC Thread
Understand that magic is not fast. No where near fast enough for combat without first "hanging" spells before hand as noted in DF 19. I recommend you read that, specifically page 17 "Casting the Spell". The ONLY difference between what is written there and here is noted in the Realms of Power thread.
For the sake of this situation, I will assume you prepared a spell per page 19.
We are looking at a strengthen light spell, making the campfire eliminate up to -4 in darkness penalties, brining it back up to what it was before.
Activation requires a verbal and gestural trigger.
Activating an incantation requires a Concentrate maneuver and successful roll against the appropriate Path skill, which for you is Path of Elementalism, so 15.
So make a skill roll at 15, success brings the campfire back to life. You can try again if you fail, but at a cumulative ‑1 to skill unless you first wait for the full, unmodified casting time of the ritual (5mins).