To reproduce this bug, wait until the mob is under 25% hp, cast this item on it, and it will heal from 10% back up to 24%
http://www.thehiddenforest.org/webtools/items.php?id=121293 Equipped on my enchanter Hafez
It took me many many hours to figure out why mobs kept healing, it was torture as I had to out DPS the recast time on this item.