With the rebirth of my D&D Civilization project, I wanted to something like this...

I wanted one of my units (in this case a Hydralisk) to shoot a unit. Ok, fine. BUT, I want the unit that was shot to have the plague effect every time he is hit (by the Hydralisk specifically).

I know that was a terrible description, but is this possible?

This is not possible, I don't even think you could do this with EUDs.

As disappointed as I am with your answer, I must say that I was expecting it. Thank you for your assistance.

Technically it is possible with EUDs - EUD actions.
The first public EUD game on b.net (some kind of masser) had tanks that shot dark swarm.

Ah, finally good news. Could you either explain the base concepts of EUDs or, even better, post the map with the dark swarm tanks?

EUD actions don't work with the current version of starcraft. All the players of your map would have to downgrade, and it wouldn't work on bnet.

EUD actions are patched in the current version and won't work without some sort of modified launcher (I think), so you can't have a hydralisk shooting a plague in the current version.

But if you just want the plague EFFECT on the shot unit, meaning the shot unit's HP goes constantly down, that could be done in a very controlled environment with a lot of effort using EUD conditions. But the method I'm thinking of couldn't be used in a D&D map at all, so you can deem it impossible, in your map. That's only up to my knowledge though, who knows maybe there is a way.

Yes, I realize that EUD actions allow such things, but why bring up something that is completely irrelevant? He wants to make a map, not a mod or something that requires a mod.

Hydralisk that shoots plague = Defiler.

Solved.

have a stacked cloaked hydralisk follow your defiler (should also be stacked)