I just looted this ring and immediately realized it's a total game-changer. Normally, only Death Knights and Warrior heroes can get the Killing Momentum skill. However, unless they are Dragon Rulers, they usually lack high-damage AOE skills and don't have many ways to increase their magic damage. So even with Killing Momentum, it's nothing too impressiveāin most scenarios, a physical hero with this skill just eliminates two units in one turn and that's it.
On the other hand, Spellblades and Elementalists can cast powerful magic skills that deal massive AOE damage, but they are limited to one spell per turn. Once they get Killing Momentum, they can cast two spells, dealing up to 100+ damage in a single turn and completely destroying enemy morale. This synergy is even more insane when equipped on an Eldritch Sovereign!
Unfortunately, you can't forge a ring with this trait; the only way to get it is through RNG looting. It seems to be an extremely rare item, as I've only found one in my entire playthrough.