unicorn acceleration

If our weight was any burden to the unicorn, it wasn’t obvious from the way the creature moved. I could feel the thing quivering in its desire to spill blood. No sooner had Butters swung up behind me and gotten settled than the beast took off. If I hadn’t ridden a supernaturally powerful equine earlier that year, both of us would have fallen off on our asses—and even so, Butters had to cling to me hard to keep from taking a tumble. The unicorn forged through the little sea of blue- and purple-armored allies who glided from its path, and then we were on open ground and racing toward the enemy.
I’ve ridden horses more than most, and I feel qualified to say that riding a unicorn in battle is an experience I was unlikely to forget.
In the first place, there wasn’t really a sense of up-and-down to the way the creature ran. In that sense, it felt more like riding a motorcycle, though I had more experience with horses. The only times I’d been on a motorcycle had been with . . .
Murph.
The pain hit my heart.
Power flooded into me, more than I’d ever felt, all of it in the space of a couple of seconds. My heart rate skyrocketed, my hair stood on end, and my body temperature had begun to climb. My brain took note of those things while my heart kept aching and more and more power rushed in.
Magic and emotion are intertwined so strongly that it can be hard to tell where one begins and the other ends. Emotion makes the most immediate and ready fuel for magical power, though it can have some odd effects on what you’re trying to do. Fuel a love spell with rage and you’re likely to get some odd side effects, for example.
But for causing pain, there wasn’t better fuel than pain itself. So, though it hurt, viciously, I fought to take hold of that power and started shaping it with my thoughts as the unicorn rushed forward. But I’d never had that much energy rush into me that quickly before.
Hell’s bells, what had just happened to me?
Flickers of green-gold light began to gather along the unicorn’s central horn, and I suddenly understood.
I had various tools, like my staff, created to help me gather, focus, and direct power.
As did Mab.
It was everything I could do just to hold on, and the unicorn had more acceleration than a Maserati. We started closing the distance to the enemy with alarming rapidity.

Battle Ground Chapter 29, Page 275-276