Player A had Dr. Doom
Player B has Golden Archer
Player B declares that he wants to use Golden Archers effect

Is it too late for Player A to use Mystical Paralysis to exhaust Golden Archer in response to Player B? In which case Golden Archer's effect would not work.

golden archers exaustion is the cost for an effect, in which case when the golden archer player exaust (activates) for the effect, it is too late for any effect to exaust golden archer. there is no point of priority, golden archer had to become exausted for the ability itself to ever enter the chain.

so, yeah it's too late to MP him.

ok, thx.

Costs are paid before your opponent has a chance to do anything. The effect goes on the chain, and you have to wait for it to resolve---not the cost.

Golden Archer is already exhausted by the time Player A gets priority; trying to exhaust him again with Mystical Paralysis would be pointless.

Edit: Beaten to the punch. I'm just too easily distracted by Metagame articles.