Give more spd to your mages, so you can cast DrainWill AND Charm in one turn by one mage. :-]
I'm almost there
i've hit that sweet spot of lvl 17 where a lot of gear is littered with + 2 speed. I was 1 action point short of making that combo last I checked. Now I probably can pull it off with a single caster. This means that in my OP scenario I can easily have 3 charmed units from the getgo.
As a player presently using a witch, I think that's the worst suggestion ever made. Lol.
I have two casters that have only 2 points in witchcraft; They are aero and pyro specialists. So I get the best of both worlds.
As mentioned in the OP I hope Larian considers, at the very least, preventing the AI from attacking their own charmed units - never mind the part where they try to CC their own charmed units (though I think the latter would demonstrate true intelligence).