What should I base an E.M.P ability off of?

I tried basing this E.M.P. ability off of thunder clap. I want it to be a non-targeted spell that slows mechanical units around the hero, damages them and prevents them from attacking (I figured I could set the attack speed modifier to 0.00 or whatever). But I want it to affect mechanical units and structure. I set allowed targets to be like that, and it damages structures, but they don't get the buff applied to them, only units do. What gives? Should I base it off of a different spell?

Did you tick the box "ground" as well?

If you want to remvoe their attack, you'll need a dummy unit to cast a modified silence over your hero that casts thunderclap.
Make it remove attacks ranged/melee and the same targets allowed as your thunderclap

OK, that may be a good idea, unfortunately I will have make both spells have 3 levels and trigger the appropriate levels and I will have two spells to modify instead of one if I need to adjust them. Another problem is how do I prevent two buffs from showing on a unit? I have this problem with another ability which combines bloodlust and rejuvination. I set the rejuvination to have no buff, but it ignored that, so I tried making a blank buff with no icon and instead it just uses a random icon. I suppose I could make a black icon but it will still be there taking up space and it will say Level "X" if you hover over it. Is there a decent way to make a buffed spell not have a buff?

Don't bother. It isn't much of a problem. No one looks at buffs.

You can't, as far as I know, but you may be able to set the attack speed modifier so high it doesn't matter anyway, since Thunder Clap slows movement and attack speed.

Yes but it doesn't affect the buildings attack speed, doesn't give them a buff at all as I said. So I will probably Use silence to stop attacks and thunder clap to slow units and do damage, it doesn't matter if the buildings aren't slowed because they don't move. As for the buffs, maybe I will just make them both use the same buff so it will appear twice but oh well.

You can always trigger it with channel :/

I was hoping it would be as simple as modifying thunder clap, or that there would be at least a single spell somewhere I could base it off of. On the plus side, I discovered that setting two spells to have the same buff makes it only show up once on the unit! Should have expected that I suppose.