Jewelcrafting 360 PendantsFollow

Pendant of Frozen Flame/Thawing/Withering/Shadow's End/the Null Rune.

Has anybody yet used any of these ? they look like pretty nice assets for Kara and other raids.

So I wonder, do the absorbing buffs stack ? do different absorbing buffs from different pendants stack ? has anyobyd checked how much damage they absorb on average ?

Well, hope someone is so well off he's been able to test these