Really? I almost solely use the dragonstone and Kamui (MAG+ LUCK-) is a beast, I can do like 30+ magic damage in like chapter 14 in the Nohr and Invisible Kingdom routes (on hard). What makes it better is that he also seems to have a really good defence so I can just sit through three turns in the middle of like 8 non-magic users without worrying about him getting killed, it sucks that it can't double but usually, it can just OHKO anyone but Mages/Sorcs and Ninjas.