^ In case you haven't noticed , aero WANTS them removed , so I am just lending a hand.
I was in a rush so I will explain things again.For the fire mastery-the bonus damage is added to the casted spell.Say you casted meltdown dealing a total of 500 damage in chapter one.Well if you picked that replace spell (and have it at level one) and your Phodom has 1000 HP , the spell will deal an aditional 50 damage.
Galeoth's spell was totally wrong , 10% is a very low number , but again aero is with the balance so if he thinks 25% or 50% is better he can do it.Icy barrage is the spell you are talking about and yes , there should be another spell that increases the autoattack DPS for galeoth because the call down for the majority of his spells is not low.