I personally gone full retard and am burning magas left and right XD. Thou I just want to get as much from them as possible, so I am using them on GvG to refill stamina, which I spent on tanuki/evolve maps to level up and evolve all my girls, this gives me BP to do more in GvG as my guild is mostly inactive and I am often alone doing anything, and then it progresses me in the event too.
So I have finished the 6* Luk99, got the 5* secondary girl for sake of TWs, and I think I passed already 50 luk on 3rd girl a second 6*. Less than 15k points to hit 100k.
EDIT:
Ups, I gone and fucked up. Upgraded Luk from 70 using 10 copies on a not yet evolved to 6* girl so I lost 5 Luk, uppsie.