The Masque

In a nutshell: The Masque is a simple unit. She gives you 3 Pavanes to reposition foes.

Pros: She's relatively cheap, and for utility...nothing to complain about, she moves units around and that's always powerful. That's about all she does really, you can get hot with your invulnerable saves but hoping you make a bunch of 3+ saves isn't a strategy for survival. ;)

Cons: Unfortunately, she has only 2 wounds and isn't much of a close combat threat which is the only place she's safe (relatively safe). So is it worth 100 points to drop the Masque and hit 2 of 3 times with Pavane? Whenever the oppponent wants her dead, she usually dies (always in KP missions). Her usefulness against mech and gojira style lists is also questionable, given how she cannot affect mech and Pavane can only subtract D6" from a MC move for a turn. As you can't pavane units immediately but have to complete your deep strike first, you can't really break up a solid deep strike defense either. Sadly, she is not an IC so you cannot ever really protect her. If the other guy wants her dead, she'll die. 3 Dark Eldar Warriors rapid firing is very dangerous indeed! Nobody else in the Daemon army will see Imperial Guard and scream 'Oh no, they have LASGUNS!'. ;)

Tactics: Drop her where she can Pavane at least 2 enemy units. If she is facing a mech army, stick her in the second wave. If you face IG or Tau, you will probably die but she can tie those guys up for quite a while if she can get into combat. She doesn't have a whole lot of use in any other way, so keep in mind she's utility and very vulnerable.

Final word: If I was running a mass template style demon army, she'd have a bit of a use but I'd still want another herald around to help me move enemies. You can make a army around 3 soulgrinders and ku'gath + masque and another slaanesh herald...but if you face mech or MC lists, you are going to have a bad time of it. I'll put such a list in for you lash/template freaks. ;) Otherwise, while good for utility...she's easily killed, so don't count on her to stay around for long.