if you exhaust zed right when his death mark pops will it reduce the damage?

i don't think so, it only reduces damage not previous dmg dealt

I'm pretty sure it is acted as an entity of some sort. This same thing happened with Tristana E,. Even if exhausting him right before the deathmark went off was able to work, it's just as beneficial if not more beneficial to exhaust him during the duration of his ultimate.

or you exaust him right after the ult, so he deals less dmaage to you with everything befor the pop, which means you also take reduced damage from the pop as it'S based on the damage he deals to you within 3 sec...