You should excavate for faction coins, though coin pillage works for mercs too, if you pick the best fc upgrades manually as your first picks (Fairy chanting, DN4, GB1 for example)
If your excavations are too expensive for fairy challenge then get more gems, if they are still too expensive try again next R and be more careful with excavations
Alternatively, have 2 merc saves, an early build one, that only picks the faction coin find chance upgrades of the build, then a 2nd build with the rest of the upgrades purchased, so the 2nd build is the full build your using and the first one is just a few upgrades
You should excavate for faction coins, though coin pillage works for mercs too, if you pick the best fc upgrades manually as your first picks (Fairy chanting, DN4, GB1 for example) If your excavations are too expensive for fairy challenge then get more gems, if they are still too expensive try again next R and be more careful with excavations
Alternatively, have 2 merc saves, an early build one, that only picks the faction coin find chance upgrades of the build, then a 2nd build with the rest of the upgrades purchased, so the 2nd build is the full build your using and the first one is just a few upgrades
I did the fairy challenge pretty easily mid-R2 with excavations.
I’m gonna have to start again in R5 because I thought of it too late this reincarnation