Faceless Void is actually bugged and that's what's making him so strong.
Time Walk moves at 3000 ms in stead of the 2600 ms he's supposed to have, Chrono is cast 0.1 sec faster than what it's supposed to and lasts 0.5 seconds too long.
These are small bugs that count for a lot, mostly making it way harder to stop void from getting off the chrono and letting him get off one hit more inside the chrono.
Fixing those bugs would make void way less op, as it'd be easier to split from a chrono in the first place. A minor mana cost increase on his Q would take him out of the offlane and back to being a carry with huge lategame potential.