Guild Wars 2

They do (almost) no damage. As they are only meant to decieve. However, why do they apply conditions?

My mesmer with S/P spec can keep 7 stacks of vulnerability and 2-3 stacks of bleeding on a target by using only clones.

What the hell man?

The do damage. The damage is scaled by your own damage.
The do apply conditions because teh condition say “apply bleeding on illusion crit”.

You can get a lot more stacks than that with 3 sword clones.