Your normal melee attacks have a chance to reduce all healing done to the target by 25% for 10 sec. This can stack up to 2 times.
Furious Attacks is a talent in the Fury tree, you will need to spend 37 points in Fury to max it. It gives your normal melee attacks a chance to put a stacking debuff on the target which, when fully stacked, reduces healing done to the target by 50%.