Chronomancy
When I mentioned the power of chronomancy, I didn't mean that being a chronomancer makes you the superior mage from the get-go. I'm just giving my opinion on its potential. I mean, you might be a max level fighter who can cleave down an army alone, but what good is that when the opponent slows time to a standstill? Or accelerates the wither of time on you until you crumble to dust?
Now, I know that kind of stuff probably isn't in d&d (aside from time stop) or atleast isn't as powerful, but I'm just shamelessly glorifying time magic :P
As for the character I'm conceptualizing/brainstorming, they'd probably be involved in a setting that has a lot more... Dimensional disrepair and stuff like that. He'd be more along the lines of "I have to fix this" than "borderline crazy". It's all being brainstormed right now though.