I get that Supports need better itemization but...
Yep it's another Knight's Vow thread,
Sooooo, it's a cool item and all but reducing the damage they take is really...unhealthy. The only thing in the game that can actually kill an ADC is an assassin but this item stops the assassin from being able to do his job. Basically if the ADC is redirecting 12% of the damage they take to their support that basically means that the Assassin is only doing 88% of what he should be but that's not even counting resistances. Miss Fortune for example has 35 Armor and 30 MR at level 6 as her base stats, Thats a little under 40% resistances, soooo ADC can have a free 52% resistance to damage at level 6 cause of this item and it only goes up. Did i mention it costs 2400 gold? Cause that's pretty dumb for such a great active along side the 100% health regen, 400+ health and 20+ armor. Not to mention the extra 40 armor it gives and 15% movement speed it gives when near your ally.
It's already extremely hard for assassins to do their job, ADC can auto attack once and not only kill an assassin but heal their entire health bar back, they don't need this riot and supports don't either. Please think very hard about letting this hit live server's.