League of Legends (LoL) Item: Moonstone Renewer

i tried this item with soraka and she do good but sometimes enemy team build gw with more then 100 % and that item can't heal ally so much also my ult R can't do nothing so i try another item called locket , anyway that was cool item at begin of season 11

I tried the item with yuumi, but i can,t tell how good it is because it doesn't seem to proc on my w (even with my passive active) like the tear does. I can't either thell when i'm in combat or not with yuumi, can someone help me on thet?