Do you mean the frozen panties? They can be obtained from the Frozen Queen in the ice raid, and are necessary to unlock the CG scenes with her when you use the memory orbs 3 or 5 (which are also found in the raid).
Dude, I think the queen's panties drop is broken. After getting all the orbs and all the legendary loot, including Tiena's panties, I only have purple loot. Now i have over 10 copies of each purple element. This is all obtained after collecting all the legendary items. That's over 50 races ... This is weird. And no frozen panties...
