Magic Resist Item that provides mana directed to tanks

My friend (fedgol) and I were playing some arams and we get a lot of tanks, and some times, we need a lot of magic resist, maybe when the enemy team is full ap or ap heavy. So we don't get to buy Frozen Heart or Iceborn Gauntlet and end up manaless a lot of times, so we decided to joke around a bit and come up with a concept for an item that would provide both things. (yes Athene's Unholy Grail is a thing but not that much viable on tanks).

It would build through Catalyst of Aeons and Negatron Cloak.

With 60 magic resist; 300 health; 350 mana

Unique Active: Activating grants one cost free ability (120 seconds cooldown)

Unique Passive: - Eternity: 15% of damage taken from champions is gained as Mana. Spending Mana restores 20% of the cost as Health, up to 25 per spell cast.