If you're going to go through with these changes to Athene's Unholy Grail

Then don't call it Athene's Unholy Grail, because it's not. Athene's is an item for scaling mages that desire a safer early game vs AP mids and the largest amount of mana regen possible. What you made is some sort of / hybrid.

THIS is Athene's: Fiendish Codex + Amp Tomb + Chalice of Harmony + 500g = 2950g 90 AP 40 Magic Resist 15 MP/5 15% CDR 12% Max Mana on Kill/Assist Increases your mana regeneration by 1% per 1% mana missing.

I'm not saying that it should be returned to that state- it was too strong even then. But don't pretend that the weird thing you came up with is still Athene's, because it isn't.

Edit: Riot's proposed Athene's changes:

• Recipe Change: Chalice + Fiendish Codex + 300 Gold = 2100 Total Gold
• Total Cost: 2700 --> 2100
• Ability Power: 60 --> 40
• Mana Regeneration: 100% --> 75%
• Magic Resistance: 25 --> 25 (Unchanged)
• Cooldown Reduction: 20% --> 20% (Unchanged)
• Mana Passive: Mana Passives on Kill or Assist have been removed.
• New Passive: Gain 15% of premitigation damage dealt to champions as Blood charges, up to 100 to 270 (based on level). Healing or shielding another ally consumes Blood Charges to heal that ally.