An easy fix for this is to simply make source skills cost 6 AP to use, then buff the lackluster ones to the same level of destructive power. This way they remain a powerful skill that changes the field of battle but now characters cannot use multiple source skills per turn (two since they currently cost 3)'.
Not sure I like that idea. If a skill was 6 you couldn't move or heal...
Not all are 3 AP incidentally - Infect and chain lightning are 3 AP but epidemic of fire and electric fence are 2. There doesn't seem to be a correlation between number of memory slots and AP required either which is odd.
Infect is excellent for removing magical armor so other spells work. It does double damage compared to chain lightning for example.
Arrow spray has always missed for me for some reason but Mortal blow is a nice skill also.
