[ArM5] 5th Ed spell design help

[Little Valley Green]

I just realised that I sent this message to the Berklist by mistake. Here 
goes again.

I have a magus in design who wants to cast something similar to "Pilum of 
Fire" in battle, but his strengths are in Muto and Rego. So I am trying to 
work my way around this limitation by inventing a new spell.

The magus can cast "Palm of Flame" CrIg 5, and then wants to cast a spell 
along the lines of either "Hornet Fire" Mu(Re)Ig 10 or "Leap of the Fire" 
ReIg 10, to cause a jet of fire to fly from the "Palm of Fire" to a target 
(in Voice Range) and do +15 damage.

Is boosting the intensity of the flame from "Ignite something very 
flammable" to "fire doing +15 damage" a Creo or Muto effect?

Dale