Again an item with proc stacks. Till 4 increment the item has a negative impact. You get increment on kill blow and they last 30 seconds. => you need to give 4 killing blow within 30 second to get some bonus. Sure i can happen, but 90% of the time it won't be the case. So as designed the ring is currently "cursed".
I think you're understanding this a little wrong. It gives you an increment each time you land the killing blow. Then the buff lasts for 30 seconds. So really as long as you kill a mob every 30 seconds the buff will stay on you (and increase if it isn't maxed). You don't need to kill 4 things in 30 seconds. In a solo/AS this is easy to do. In a heroic I'd say it's almost easier due to mobs always coming with friends. Personally I don't like the rings myself because I feel I always start out at a disadvantage to the fight, but dem resists tho.
