Q:
Mesmer illusions' damage is 0?
A:
Illusions do very little damage, by design. Their basic function is distraction and Shatter fuel. Some of them do other useful things besides damage (Sword illusions will apply vulnerability, Staff illusions apply random conditions to enemies and buffs to allies, ect) and there are a number of traits you can use which add other functions to them as well, such as Sharper Images (Duelling 15pt Minor) which lets them bleed on critical, or 3 different traits in different trees that cause conditions to nearby enemies on clone death, among others.
Phantasms are the ones that actual deal any sort of noticable damage, though. If you want damage-dealing minions, go for Phantasms.
As for illusions not holding aggro… sometimes they do, sometimes they don’t. Depends on enemy type (some enemies, especially Risen, tend to completely ignore all summons and go for players directly), proximity, and other factors. Doesn’t help that they never really get time to build aggro since they tend to come and go quickly.
Thanks Electro, that sounds solid.