The spell also has a change to proc the following 3 effects on the wizard for 8 ticks according to lucy but I think its less.
Concussive Chill : http://lucy.allakhazam.com/spell.html?id=10887&source=Live
Concussive Flames : http://lucy.allakhazam.com/spell.html?id=10886&source=Live
Concussive Magic : http://lucy.allakhazam.com/spell.html?id=10888&source=Live
Each one does the following for that particular spell line,
1: Decrease Spell/Bash Hate by 100%
2: Limit: Max Level(75) (lose 10% per level over cap)
3: Limit: Effect(Hitpoints allowed)
4: Limit: Combat Skills Not Allowed
5: Limit: Resist(Magic allowed)