Support Item concept - Mana battery

What if there was a support item active that allowed you to lose current HP in order to restore some mana? Sort of like a (W) except it restores mana?

Cost: 2300g Recipe: + + 650g +40 Ability Power +10% Cooldown reduction +30 magic resistance +100% base mana regeneration +7% movement speed

Passive: UNIQUE - HARMONY: Gain +25% base health regeneration for every additional 25% base mana regeneration. Active: UNIQUE - Consumes 20% of current HP to restore mana to targeted ally for the same amount. (60 second cooldown)

Edit: Would it be better if it drained own mana instead of HP?