Hmm I was looking at the Warlord stones, I believe the one that's currently labeled as ??? is the Dance of Chaos skill. I have the lvl 2 stone that I'm almost certain I got from a WB chest skill pack thing item. Now I need to get the lvl 1 :\
Could you post a SS of the stone? i had it listed as "Abyssal Slash" before the revamp and going back through this time, I realized I was one 'damage' stone over and 1 'duration' stone short. So I left it as '???' for the time being.
Dance of Chaos (Level 40) (Berzerker / Warlord)
Lv 1: Black Flame Ruins (Mission Order) (may also come from Temple Colosseum, not sure though)
Effect: Permanently increase the duration of the skill by 1 seconds
Lv 2: Obtained through World Boss skill chests
Effect: Permanently increase the duration of the skill by 2 seconds