New idea: Ranged Tank

Let's make a ranged tank. But to be "fair" He will only be an invincible tank sometimes. The rest of the time he'll be a ranged fighter with massive sustain, kiting ability, a double-escape, and a speed boost.

Oh, but don't think that just because he can do Vi's damage and is as unkillable as Nasus, that he won't have CC. He'll be able to stun or knock back every enemy with his ultimate and slow every few seconds. But to make the slow fair, he has to catch it on the return (it'll be a boomerang). And if it's dodged, don't worry, he can make it hit on the return as well.

Doesn't that sound like a good idea for a new champion? How is it not completely obvious I'm talking about Gnar?