I'm calling it here: Knight's Vow is HAWT GAABAGE. Don't buy it over Locket. (Using actual logic)
Why? Let's think of it like this:
passively reduces damage by 12% for someone you tether to and gives you 12% life steal from enemies damaged by your partner. For every 100 damage suffered by your designated ally, you passively remove 12 of it from your ally and take it yourself as true damage after mitigation. Meanwhile you gain 12 hp for every 100 damage dealt by your partner.
gives an aoe decaying shield that grows in strength as you level up in the game.
Most supports are primarily concerned with protecting carry champs...usually a marksman but sometimes apcs or carry junglers (maybe even hard carrying top laners). If a support buys this, odds are it's going on a marksman in most instances, right? So for every 100 damage your marksman takes after mitigation, you take 12 of that as true damage and let your adc bypass that damage while he tries to heal you back up by landing hits (remember...12 hp per 100 damage dealt). Meanwhile Locket's an aoe shield every 90 seconds.
So let's look at the hp of a marksman by level 18. Say...eh...Jhin, the bot lane marksman with the highest level 18 HP (unless I missed someone) at 1985. Assuming he didn't build a Cleaver or a Randuin's or whatever, Jhin can take 2223 damage before dying assuming you linked him up to a Knight's Vow + you have a decently healthy HP bar. That's about 238 more health value from his original max health. Locket, on the other hand, can take UP TO TRIPLE THIS PER PERSON AROUND YOU AT LEVEL 18 INCLUDING YOU YOURSELF so long as you don't misfire on accident. So this item blocks more damage on Jhin than Knight's Vow does off the bat on top of protecting more people.
But we're not done yet. Locket also synergizes with heal/shield multipliers, so that 665 at level 18 with just Redemption gains an extra 65 shield power per 10% heal/shield multiplier you have up to 50% (in accordance to the max amount you can have in the game). Just Redemption can get 665 to over 700, but all of them at once gets nearly 1k shielding PER HEAD by just pressing Locket. Meanwhile Knight's Vow is still applying true damage to you to allow your Jhin to survive only 238 more incoming damage. Any more and he dies. To boot, he only gives you back 12% of his damage dealt after mitigation as well.
So why use Knight's Vow over Locket when you get more value by just paying attention to incoming projectiles and then pressing a button? Some people tell me that Knight's Vow is actually "really good", but when you have this in the back of your mind, I can't see how you'd get to that conclusion. If you can HONESTLY make a strong case for why you'd build Knight's Vow over Locket knowing this info, please do tell.
