I've played the masque a couple of times. She's usually dead right after her shooting phase. Recently though someone informaed of the technique of using multiple independent characters to assemple a unit around a character such as the masque, who is not an IC. Due to daemon special rules, though, the only unit this works with is the Herald of Slaanesh. So I could pile her in a unit with two or three heralds and make a weird mess. You can give those Heralds all Pavane, too. So if you were crazy you could give the Heralds Pavane or Demonic Gaze and mount them on seekers. if the combat starts to get close you could move the masque out of coherency, pavane your attacker, shoot with the heralds and charge into assault.
they are rending too so this double****s eldar wraith lords!!