Sounds like a healing spell to me. Still, even if it was just combative or supportive, magic is magic. That means you're familiar with it and don't need to be taught about it.

What you'll need to learn, however, is how to channel your magic through your horn.

(The unicorn taps her own horn.)

I may not be too familiar with a changeling's potency for magic, but I know they at least have some. Try channeling magic to your horn; don't worry about using it yet, just focus on your horn.