When target casts a healing spell this spell has a chance to cast Mana leak on target of spell cast. This effecdt will trigger an average of 2.2 times per minute.
There are actually several Defensive Stance sets with the same name and effects. Items from a different set will not contribute towards the set bonus in another set. In other words, you will not get a two set bonus for just wearing both a Druidic Bracelet and a Stone Tower Earring, since they belong in different sets.