
And below is a damage comparison for spells at TF levels 30, 27 and 25. I wouldn't recommend multiclassing more than 5 levels, the drop in damage for some high level spells and difficulty in penetrating SR makes it a hard sell.

No spells below level 3 were added in the comparison as their damage output is generally too low to be competitive. Over time spells were not compared because that's a headache to calculate. Observations of note are walls of fire/ice that are more effective with empower than maximize thanks to only containing 2d6 as damage variables, both can be stacked infinitely in the same place with themselves and the other wall spell, and WoF deals double damage against undead. And that Firebrand becomes more useful for damage dealing against 3 or more opponents than IGMS, presuming failed saves. Against crowds of 6+ it wins out even if they all make the save. Finally, sound lance outperforms its other elemental counterparts thanks to doing D8's of damage and not having friendly fire.