Prototype: Omnistone - New Ohmwrecker
Let's have a continued discussion on this. I'm not the highest skilled player by any means (~high plat/mid dia) but I do have a couple of friends whom are and share the same opinion throughout our discussions as myself when testing and using the Keystone.
It's uh... well, to put it bluntly; very useless. There is no situation yet found in dozens of games where it felt like it had impact. Most of the time I wouldn't even notice what Keystone I had on even though it's displayed adjacent to the Health bar. The runes it did give me most of the time had little-to-no effect and I would've been better just committing to one rune instead of changing my play-style to fit what I was given.
My opinion isn't worth too much, and neither are the friends of mine as we're not pros -- but I don't see this rune ever being used. Kleptomancy was removed because it was only used by a few champions; namely Ezreal, Miss Fortune and Karma among others, as well as being hard to balance. It was replaced with... a much worse Spellbook.
Thus I'm naming it Ohmwrecker instead of Omnistone. It's niche, it's bad, and it absolutely will not see mainstream appeal in it's current state.