I think this problem means that, from the begining, two heroes keeping attacking the creep without a break, and adding the disease hurt, you to determine the creep will die from which one, but I also see there have no AC on this problem, that make me doubt with my thinking, is my idea too foolish? eh.. maybe I got in a strange way.

But if "optimistic strategies" means the two heroes both waiting the time that his one hit can kill the creep without attacking the creep any hit before, eh... that's make the problem boring. If that, the problem is:

Hero A calculated that if his bullet arrive the creep at X sec, the creep will be killed, and his bullet takes Y sec to fly to the creep, then he will shoot at X-Y sec; And the hero B is the same.

That some of my idea, god knows that is correct or wrong.