Disable autoattack

Is there a way to disable autoattacking so unit attacks only using trigger (order to attack once)??? I thought about making an ability but I would prefer to damage the unit based on strength etc.

Units with worker classification don't auto acquire targets, but they also show an icon in the bottom left corner of the screen. Besides, the player can always manually order the units to attack; unless they're dummy unit with locust, in that case they shouldn't show the icons either, so worker classification should work for you.

or set a units acquisition range to 0.

Hoever, I dont think this will work when the unit is being attacked.

acquisition range of 0 doesn't really work

Well... I tried that acquisition range before. I'll try to make some use of variables, so if variable is false just stop when unit tries to attack.

Have you tried anitarf's suggestion? That would work.

If you add the worker classification through triggers u wont have the icon but still have the i-dont-fight-unless-i-am-told-to effect, also setting can flee to off will just make the unit stand in place when attacked instead of run away i think.

For caster system I had to use negative line of sight . But even that didn't work sometimes, luckily blizz added the damage functions and I no longer needed casters to have an attack

Use permanent invisibility, but set the duration to -1 (have to use shift-click to do that) and 'Auto-Acquire Attack Targets' to false. That makes the unit never actually become invisible, but the unit still won't auto-acquire, because it's trying to go invisible.
They will still auto-attack units that are attacking them, though.

I'll try shadow/anitarf solution...

@VeX:you got < br > tag stuck between rep blocks :)

EDIT: Works perfectly.