Resist Check and Charm Question

[Baler]

Enchanter
200 CHA + 59+ shaman = 255 cha
205 CHA + self buff = 255 cha
>255 CHA buffed is your goal!<

Make sure the mob is tashed and preferably malo'd. Give it -magic resist items.

Yes if your tash ends on the charmed target it's MR goes up and it gains chance to break on server tick.

Your CHA + Targets MR + Your Lvl vs Targets lvl are all known to factor into enchanter pet breaks.
It's not a duration or a timer. It's a check every server tick. You can literally have your pet break back to back, over and over if you have bad luck.