It seems that the fantasy rebirth system has been neglected for a long time, only sporadically adding to some friends at random, which is a shame because it has SOOOOO much potential. Especially in regard to older friends like l1, old A-fes where their ability/skills/spell cards has not been kept up as time goes on, which while the 2.0 try to fix seems not enough. The 3.0 rebirth which target their ability could boost them to be able to catch up with modern friends.
This can allow friends to add barrier status like l1 reimu have def buff for burn/poison, l1 sanae absorb paralyzed; or boost/graze ability like l1 kanako have accuracy boost; or even add dmg to res/eff up or dmg from eff/res down. It can also tie to the lore and to other universe like l1 to l80 or l1 to l0g/l0o (see reimu l80 and what i buff for l1 reimu).
The price would be like 1000 mirror, some scroll, tile, paper doll tie to friends rarity (4 for l1, 3 for a-fes, 2 for ultra-fes and 1 for the other rarity: relic, epic,....). If you want people to not hoard dolls you can do this and to increase number of dolls exchange in event to balance it.
#Fantasy rebirth for friends ability (3.0)
fickle arrow
dusk veldt
+1 also would like upgrades to old units with FR that haven't been given any kit upgrades
hazy fog
+1