I get that assassin's wanna avoid being seen, its important for their assassination but, I think it should change
instead of disabling wards, what if it just detected them?
give it a big detection radius (bigger than ward vision) but use a pointer to tell the champion which direction the ward is
kinda like how soraka's passive, knights's vow and zeke's convergence all have pointers
http://1.bp.blogspot.com/-6hfitMaH-DQ/VA-B18hTXEI/AAAAAAAAYBU/I9sQDD_Sevc/s1600/soraka.jpg
not sure if it should mark the ward's location but it should be completely passive
this way assassin's get to avoid being seen but not in a way that removes vision entirely
evelynn for eg knows only pink control wards reveal her, so maybe she'll investigate in case its one of those
talon and kayn however can use the information to find an alternative route for a gank