Ghost Cloak:
Cost: 2500
40 Armor 45 MR
Active:
Become Invisible for 4 seconds. (You can move) Cooldown 90 Seconds
(If you hit someone within those 4 seconds they will be able to see you.)
(If you are hit by something like 
Q you will be seen)
+ 
+ 1400g = Ghost Cloak
Taking bushy garen to a whole new level
Not sure if serious but holy that is OP beyond imagination. The unseen champion is the deadliest
Umm... Nah. Doesn't give increased stats beyond the components. Doesn't really have a true purpose. Makes assassins strong, but doesn't serve any AD for it.
And wtf is this?
It's CHEAPER than Guardian Angel.
But hey, that's just me.
It'd Have to be without moving, but honestly, any item that gives invisibility could break the game, the same items that give dashes (like blink dagger). The best examples of using it would be like Eve's passive or Teemo's, but that is just copying the unique trait of another champion. To make it unique, it can be a speed item, not an armour item (ignore unit collision and get a passive ms buff). When you enter brush "out of combat" you can go invisible, you are revealed if you are hit by AOE, attack someone, or take DoT damage. You can maintain invisibility when you leave the brush, but only for 2-4 seconds.
Put simply, it should only grant invisibility WHILE you are already invisible, like a ninja shroud, if someone sees you do it, it's obvious, but if they don't, you can catch them off guard.
So similarly, while out of combat and out of sight, you can go invisible while static, becoming revealed upon moving or taking damage. It'd be ideal for split pushing and counter jungling, but useless in an actual fight, making it a niche build.
