Did some experimenting on easy mode and I'm starting to really doubt if a pure agility charm build is possible, or at least, not the way I thought it would work. Did the first floor boss fight w/51 agility and 44 charm and 13 slut level. Nobody can hit Karryn, but even w/44 charm it takes *FOREVER* for prisoners to finish themselves.
Best use of charm I can see so far is to get prisoners aroused/erect so you can crit them more easily and do the ball kick. This also leads to a high sadism stat, but I'm not sure what sadism actually does.
The main advantage would likely be the fact that prisoners don't attack you whenever you charm them, them finishing themselves off is just icing on the cake when you are fighting against fodder.
Bosses are probably ultimately intended to be taken out directly through either combat or the other physical alternative.
Also note that you can grind stats and passives for a build, lose, and carry over all your grinded progress into a new Game+ on the same or lower difficulty. Once you hit the Warden level cap, you can try to defeat the boss to unlock the next stage and level cap.
Game+ and the Warden Level cap lets you defeat boss characters without leaning your build in a direction you do not intend.
And as far as Charm goes, I noticed that I need to level either my stamina or energy statistics in order to not fold over like a squishy characters and lose engagements.
For combat you can just eliminate the enemy faster than they can eliminate you, but with the slow burn charm statistic, you need to level up your durability stats in some way ( Stamina, Agility, Strength, Energy, Mind, Endurance ).