Illusion isn't great with containment... you've got Flash and Blind and that's it. Your damage is more going to come from Phantom Army than from yourself, here's my experiences:
Illusion/Dark - my only Illusion 50. I've got Perma-PA on this build so she really shines on both teams and solo. I took Shadow Fall and Group Invisibility (since Shadow Fall and Superior Invisibility are mutually exclusive). My set up is PA/Spectral Terror/Flash then Tar Patch then just Blind->Spectral Wounds->Blind
Illusion/TA - Currently about 33. This build I don't plan on IOing out beyond commons. Entangling Arrow helps you set up some additional containment, especially on EBs/AVs which are affected by PToD. My plan is to take everything in both Illusion and Trick Arrow mostly because everything in both sets is solid.
Illusion/Storm - Currently 20. I'm planning on a build that will get Perma-PA. This build is all about havoc, while my Ill/Dark has -KB slotted in Phantasm, this guy is all for knocking back. Freezing Rain, Tornado, Lightning Storm, Phantom Army, Water Spout are/will be my damage. Taking Steamy Mist and Group Invisibility for the same reason as Illusion/Dark.