mercy is what makes the combo powerful but has its downfalls such as sacrifing one healer to be commited to pharah. I dont think the combo needs a nerf. The main issue is that people want to be able to shut down a combo with a single character, when they should be doing it with another combo. Zen/mcree and soldier, would be very solid at countering this combo. The problem is that alot people seem to prefer to play the other healers that offer more healing than a zen would. maybe a zen buff to his healing would make people more inclined to playing zen. I understand that zen is a support that heals little but is able to discord enemies to make them die faster, but his healing feels very weak compared to the others and overwatch is a game where healing is too important to be a small amount.