Yesterdays patch message stated that Tainted Carress was fixed and that it now works as intended by summoning a Tainted Essence (% chance per attack) which is used in summoning the ShadowKnight pet.
I knew of this problem of it not working correctly, however, despite the patch notes I have not had any luck in obtaining any tainted essences. I was basically wondering if other SKs have noticed this, or if it was just a run of bad luck on my part.
I spent 4 hours soloing and casting carress on each mob at least once, and some fights twice. I even soloed mobs with straight melee and no abilities beyond carress.