PUBLIC SERVICE ANNOUNCEMENT _____________________________________________________
Anyone planning to have Minthara in the party during a paragon playthrough; DO NOT KNOCK HER OUT DURING THE RAID IN ACT I.
Do it at the Goblin Camp instead, otherwise you'll end up with this permanent annoying bug causing her to globally keep pulling Cerys into every single combat encounter throughout ACT II and ACT III, as the game keeps unloading and loading entire areas whenever she gets her turn.
It is possible to get rid of it without murdering Cerys, however it is not 100% guaranteed. After a lot of testing the bug seems to be tied to two side quests;
Lift the Shadow Curse (Halsin)
Rescue The Tieflings
During my testing Cerys would only stop joining the battle after completing Halsin's quest and then talking to the Tieflings at the prison. Other variations of events did not fix it and to make matters worse it is not a 100% guarantee fix, because under the exact same circumstances this bug would sometimes continue to persist... but when it does work it works for the remainder of the ACT. So complete Halsin's quest entirely first and then talk to them at the prison.
*As can be seen Cerys stops joining global battles if everything goes according to plan*
In the meantime Larian is aware of the issue and working on fixing it.