Athene's Unholy Grail "very likely" in next patch.

The last incarnation of AUG, taken from the PBE

Straight from the mouth of Nerf Master Suck Town to your ears; Morello had this to say about Athene's Unholy Grail's upcoming addition to the game:

We had to do a little more work on this item - it's very likely you'll see it in the next champion's patch.

- Morello, Lead Champion Designer, via the official  forums.