Shadow Blade
I was mixing around thoughts for items that can add a tactical advantage to some team fights or just during lane, and I came up with this. The basic concept is as follows.
The Shadow Blade 30 Attack damage 15% critical strike Unique Active - Into the shadows - When activated, grants the unit 1 second of invisibility. (If damage has been taken by champions or large minions, it takes 3 seconds to activate)
The general idea for this was a twitch like style. You get your invisibility which would allow for baits by your support, or to just get up closer before being seen. I find is relatively easy to balance as well. The invisibility doesn't last quite long enough for it to be overpowered, but allows you to get into better positioning for amazing plays.