this bug seems to be with pausing during the cutsceene....
With raze for an example the quicker you get though the cut sceenes with him the less explosions you get as soon as the battle starts.
since his normal magic attack is a single explosion it seems he is cueing them up while talking and then unleashes them all at once.
the player also seems able to do this.. with magic missiles jump up from behind cover... then as soon as you fall back behind cover the enemy stays targeted for a split second you can actually launch machinegun mode 3-4 barrages of missiles in a split second the faster you tap the more you shoot.