This talent has so much room for abuse it will never make it live without major restriction on boss abilities.
I am aware these are MoP talents but since I don't have any MoP bosses to go off of I'll use a 4.3 Boss, Pretty much every boss has something that can be abused.
Stacking 10 locks (not that unrealistic in a 25 man raid)
Quick example
Warlord Zon'ozz
Void Diffusion - When the Void collides with a player it diffuses, inflicting 807300 Shadow damage split evenly between nearby players. The force of this diffusion causes the void to richocet in the opposite direction, and the absorbed souls increases the damage the Void inflicts by 20% per diffusion.
1 warlock acts as a blocker each time using Sacrificial Pact to prevent death, once they have all done a rotation they start to sacrifice themselves, imagine the following,
So if there are no restrictions AV will do circa 61kk damage.
I can think of so many bosses where this could be abused to completely destroy an encounter.