Foul gift is pretty good since it gives me INT and it has low ICD (45s) plus the 1.2k mastery proc
The soulshifter vortex gives me stamina, that i dont need, but the proc is insane 3k mastery for 20 sec, another negative thing from this trinket is the ICD, that is around 100-110 seconds
So its like.
Soulshifter proc = you can destroy the target.. but u have to wait a while to it happen again
Foul gift = consistent damage with low icd proc, also INT..
Defenetly Foul Gift all the way. Soulshifter to the trash.
PS: You wrote "I bought", I hope you know that dungeon from which you can drop this trinket is open. I belive its also obtainable for Conquests on Warsong.