To coincide with this update, the game is also reworking its stealth mechanics, splitting stealth into two different categories of stealth and invisibility while also giving players new ways to locate stealthed characters by hitting them and causing a “shimmer” effect. The result should be a more interesting game of cat and mouse for players; check out the full notes for all of the individual champion revamps and more details on the stealth shifts, as well as items and new plant life.
Source: Official Site