People need to like super tight and not move around to much.
Never had an issue when I play him but when other play him they move around and I am dead.
Also latency is a big issue.
Zen doesn't negate Immediate Damage. It's more *dmg, heal*. Like as soon as the damage is done, he heals. If there's nothing to heal after the dmg (I.E. It kills them) then ta-da, he can't heal.
Because of the same reason it doesn't cancel out D.va's ult.
Burst damage does a single damage value thats over the max health of the victim. Hanzo's does damage over time. Damage over time can be healed, 1 hit KOs cant
Junks is burst, it does 600 (I think) damage all at once, which is enough to one shot most heroes, and zenny ult heals 400hp over the course of a whole second