New Rune suggestion for Tanks?

Absorption 1: After activating a shield and expiring, you will absorb the remaining shield for 100% of it's value as HP. Absorption 2: After healing passed 100% HP, heal up to double your maximum HP level - that slowly decays over time.

It will be good for tanks who can't lane anymore, and not quite OP because ADC's are doing at least 500-700 damage per auto-attack, not taking into account abilities.