Have in mind that PS last 8sec while Surge is 10s. That's not only bad part of it. PS also reduce your threat, have that in mind and tell it to your casters.
I have usually 3 paladins with me for Vezax so I'm alternating sacrifice/buble with shield wall. My healers are going for green cloud when Vezax is at 30-40%, still don't have hard maths if it will work in hard mode.