Thread: What are spirits used for?

Originally Posted by Tenhou

They are used for 2 things:
1. To evolve units.
2. To boost experience gained when you combine.

You should save enough of each spirit so that you can evolve the units you want, and especially save any plat/black spirits you get as they are harder to come by.

except iron and copper fairies, which are mostly used as bonus experience when combining. (also known as fodders)
copper fairies are slightly more useful than iron fairies though, since there are some instances of using them to level bronze units faster (to mincost + max level)

as for using fairies to combine, if you use the same rarity to combine i.e. silver fairies with fodder unit, into a silver unit, the silver fairy makes the fodder unit's exp x2. (x4 if you use 2, and x8 if you use 3). otherwise (e.g. iron fairy with fodder unit into silver unit) , it only makes the fodder unit's exp x1.5 (x2.25 if you use 2, x3.375 if you use 3)