1/ basic idea. Nothing wrong. Maybe too much like kido's arrow
2/Silence debuff at 7 sec is way too long (even if it doesnt active when not moving), check those numbers again ^^
3/Again passive bit op. Its like all your ally in 400AOE has more evasion than if they all had gg suit.
4/The gang skill? I won't put him as ganker since the only gang spell is the ulti which has 40sec cd. Again, a mix between zab and ass cloak efect even if invisible + blinks in 800range can be good
I don't feel like theres much synergy in all that, moreover no spells really make him as ganker or even semi-carry (looks like more a diabler). Your suggestion has potential but needs to be reworked, synergy rethinked and numbers re-scale.
Idk if you saw that one from mercinater
http://www.nwu-forum.net/t724-am-kushimaru-kuriarare . Can be a good idea to check him.