Having the option to use Vigor in some spells

That was a sneaky bug. It was caused by prematurely setting 16-bit memory before calling the magical damage code. This can cause the carry flag to be wrongfully set sometimes, resulting in skipping the quadrupling of Battle Power/Spell Power that gets added to damage. This is normally only skipped by Items, Runic and other "special" forms of damage/healing that do damage exactly equal to Spell Power.

You may have noticed that the difference in damage was exactly Battle Power * 3. That's what clued me in to the bug.

It's fixed now and I updated the code in my post.