I can't really see the point of using enervation spells such as Plague / Master Force Scream / Choke when you could simply outright "Kill" her after activating your Master Valor. The difference between a 100% success and a 90% success is simply not considerable.
http://postimg.org/image/cikbfx6gz/
Also my character has 55 Wisdom & 25 Charisma and the reason why my Force DC is 77 is because i used Force Mastery.