[MothEnthusiast]

Also to OP's point, I don't think halving chain unsummon's damage would be enough after seeing it in action recently. Getting 100+ damage per youkai unsummoned is insane. 60 damage is plenty. Make the first instance undodgeable and unresistable, and all subsequent in the chain be dodgeable and magic armor ignoring but remaining 60 base damage. That's still 30+ per for a pretty beefy hit in total.

Make sthenno one proc per turn.

Make youkai take the hit of their summoner's mainhand weapon.

The youkai double-turning thing is annoying, yes, but I think ultimately it isn't the real problem of Grand Summoner's kit as a whole. I think start with the above changes and go from there.