What are spirits used for?

[Unregistered]

I'm kinda new and I wanna know what the spirit fairys that some challenge quest and daily quest drops are used for. There are iron/bronze/silver/gold/platinum... i'm guessing they're like units? if so then I should save silvers/gold/platinum for CC?

Thank you.

[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.

[soranokira]

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)

[lolix]

Now keep in mind what sora said , and remember to save fairies ( especially of platinum - sometimes gold - and up ) to use with platinum armors that give xp , obtained from monday dailies or various events. 1 platinum armor gives 2k xp to a unit. combine that with a fairy of the same rarity as the unit you want to combine , and you would get 4k xp. combine with 3 fairies , and it would give 8k xp. 8k xp is enough to insta lvl a unit to lvl 40 or so , but you should generally use that when your units are already cc-ed and past lvl 50 because combining then takes a crapload of gold

[ZeroZet]

Basically, Fodder Units
You can find the nifty table on plat armor (a.k.a tin can) + fairies usage here

[Unregistered]

Thank you everyone for your replies.