Character that loses memory due to magic

Okay, first, that sounds pretty cool. Second, I think sometimes they should get it back painfully slow, like just one memory at a time, but other times a bunch of memories just come out of freaking nowhere and knock his socks off. But that's just my opinion.

No problemo

I have several characters that lost their memories.
Kyro was hit on the head by falling rocks, Slaise also lost his memory (not going to spoil it).

I have a story idea really similar to this.

I hope this helps: The story of sad, confused twelve year old me (I'd just finished kingdom hearts and I loved the idea of memory loss) trying to write an idea very similar to yours. What happened was more of a "what not to do when writing memory loss" tutorial. Here are some tips I learned 140,000 words later.
-Bring the memories back slowly –but not too slowly. You don't want to reach the end of the story and realize that there are some gaps you haven't filled yet, and then rush to fill them. Take your time on the memories, but don't act like you have all the time in the world.
-Hit important, relevant information. Don't introduce memories that are unnecessary. Any memories you do introduce should be relevant and current.
-Don't clutter the narrative with too many flashbacks/dreams. If you want to have flashbacks to show the memories that your character is gaining, find the right space to do that. If there's something important going on, and all of a sudden your character is hit with a flashback, it's kinda disconcerting. Treat flashbacks like scenes/chapters of their own. Don't throw them in randomly.
Have you ever seen the animated film Anastasia? It's actually a really good example of memory loss/regaining memories slowly. Plus, the animation and songs are fire, so I recommend you watch that to get an idea of how to introduce regained memories. Good luck!