Ok. So, how this works is that you need to repeat an incantation. You can do this in your head, but as long as you focus on the words, and only the words, you can cast the spell. I find it's better to do it in your head, since you need to concentrate anyway. The words are "Riktar, Shicktar, Paktar, Rejuve" (ric-tar, shick-tar, pack-tar, Re-joov)