Board Thread:Off Topic/@comment-25396609-20160923220030/@comment-26397825-20161103044556

Think of it like a Overdrive bar in games for mages. You activate the overdrive, it uses a little bit of mana to activate, and then while it's activated you have a set time limit to use as much of that Overdrive bar as you can. Once the time limit is up, the Overdrive and any remaining mana disappear, and you are left with your original bar which is untouched outside the initial Overdrive activation cost.

It's tied to a substance so the user can't just abuse this, which has clear and set amounts of Overdrive it can create, and the weight and size of the substance (in this case being sugar) means they can't carry an unlimited supply.