I was playing the game casually with my sister and noticed that in the ruins, just outside the portal to the maze, there is a light crystal that gives you the light unicorn spell. It would only be a small detour from the current any% route, so if there is any use for it, it wouldn't be hard to save time.

Light unicorn gives you increased run speed and a double jump... When going in a straight line it's slower than spamming the dash, but I'm wondering if there might be any uses for it

I ran some tests on this a while back when first attempting to route, but blink is just that broken that it beats out all the other speed-up abilities by a wide margin. Blink direction is also tied to your camera, so you can dash vertically to reach any height you'd get with the double jump.

There's one niche use for it right now, but it's only relevant for 100% completion routes (which we're still a way away from seeing, I reckon). If you jump into the ruins portal and activate a power in midair, you can 'smuggle' the ability into the maze, bypassing the "no magic" restriction that's usually there on the inside. Smuggling in light/fire unicorn helps you run through a little faster, which is a good plus since you obviously can't blink in there. But yeah, there's no story/horseshoe content tied to the maze, so this tech won't show up in any runs for a while.

I would additionally add that the blink doesn't seem to trigger certain triggers such as the Void Portal activated with Baersha. In terms of use of magic in areas where it isn't allowed, it is actually possible to activate it inside of these areas using the rest mechanic. If you start rest, then hit any of your powers very quickly after de-activating rest, you will not only do that ability, but also regain control of your magic as it seems that the game only locks your powers once and doesn't check it again.

Welp, that's a shame... It is cool that it (almost) had some use right next to where you find it, but I guess Blink really is just that broken