DarthStoney

just have to make nihilus hard so there is a temptation to have Visas kill her self since you will fight the weakest version after that,..

You just have to have somewhere in text during a conversation or part of teh fight scene where the Pc talks /thinks in his/her mind that...Visas's connection would greatly weaken Nihilus and give us the best opertunity,..just as the bond with kreia can hurt me

The other options will also have a version that is stronger than the visas kill self but weaker then the original version since Nihilus.

Now with Nhilus and PC lie to join,..dont know how that plays out but you can see where that can play in but have basis sacrifice the greatest help in weakening.

also you will have to have it so Visas can do this sacrifice even with robes on or what ever