that tier is supposed to optional, meaning no talent is optimal. they didn't like Sac being the best option, so they've made it the worst. seems short sighted to me, they clearly dropped the ball designing the talent because of scaling issues. it would make much more sense to me to make GrimSac function like a pet but without a pet. you sac the pet to choose the utility, and then you gain an ability like Cunning of the Cruel that does passive shadow damage to your current target equivalent to what a pet would do, scaling with haste.