What does overcharge actually do?

I was searching around on the Internet for the answer for this, but the only information I could find was for class specific build information.

I just started playing tonight, and I'm not really sure what overcharge does. Is it simply a limit on how much magic you can cast, or does it actually give you a buff? It doesn't seem to make a difference on damage against the training dummy, but the segments on the meter, and the different stages of the burning effect make me feel like it's supposed to do something.

@mvhvtmv: When the bar fills up entirely, you blow the hell up and die, taking a few rats along with you. It's a limit on how much magic you can use; but every once in a while, sacrificing yourself to take out an entire horde of rats can save the day. Additionally, overcharge plays a larger mechanic in the other two subclasses for the bright wizard, increasing crit chance for the single-target class, and acting as a shield for the melee focused build respectively.

@do_the_manta_ray: Ahh, fair enough. Thanks.

I knew that you blew up and died when you were full, but I just wasn't sure if it was actually making a difference between empty and dead. It definitely seemed like it should be doing something, haha. Good to know it does make a difference, just not for the default subclass then.