I once played a version of DOOM II on sc bnet, and there was this Dark Archon Sniper who could MC a guy and it would kill him like that. I wasn't sure if it was just a normal trigger bout controlling a unit or whether it was the actual mc which triggered the death.

I was wondering if it was possible to like say, use a Ghost to Lockdown a unit and blow him up on contact with a trigger?

and last quick question is it crashsafe to reformat a map into unconventional sizes?

Nope, it's not detected with the spell - Lockdown can't be detected (as far as I know). For the mc, it's just a trigger that detects who owns the unit - pretty simple.

Changing a map for sizes other than 64,96,128, or 256 can cause crashes.

A map that has odd dimensions will usually not crash if you play another game first, unless it's like really small or too big.

Keep one dimension of the map size conventional and you should be fine.

There is a way to detect lockdown. But its not absolutely reliable.

You can use the fact that nearby enemy comps will charge in on locked units. The radius is far higher than the sight range but also far lower than the smallest conventional mapsize 64x64.

So place some cloaked computer wraiths (or whatever) with extreme damage all over the map (try to figure out how tight the wraith-grid has to be to cover everything). Blinding them will reduce their normal sight range which improves stability as they will not attack nearby non-locked units.

And after a unit has been killed move every wraith back to its place to prevent further kills. This should be hypertriggered.

Also you could just detect the wraith's movement (and set them back immediately) though this way you couldn't tell WHICH unit has been locked except you only have 1 mecha unit in game.