Wow, my friends csm worked exactly the same way, except in place of the obliterators he had a Dreadnaught with Havoc launchers. Then he got a pretty butch lord of some kind, a pack of daemonettes, and usually some type of a fast attack squad, rapotors or bikes or something.
Unfortunately, I never got to face it with my eldar, I only did DE against it, but I got pretty good at whipping butt.
1) Play a mission with some kind of objective, not rampant slaughter-fest.
2) DON'T let him force you through a column like that! If terrain is set up in such a way, object!
3) Forget the fact that you're getting nailed and go for the objectives.
That was my basic strategy. If those launcher squads don't move thats a lot less of the army that you have to deal with when attacking something like take&hold or cleanse.
Don't try to engage the marine squads with missile launchers, you expend a lot of recources doing nothing. Instead hit the defiler, and anything he has that is fast. After that your quick eldar units will gain a slight advantage.
Forget about the Wraithlord, that many missile launchers makes T8 look like a joke, just leave it at home. Instead take a pair of skimmer tanks, of the falcon variety most preferably. Missiles don't work too well, and if he does down one he probably shot a lot of his army into it and it drew a lot of fire. Just like you said hull-down it and let er rip. That or advance both along a flank and try to cause havoc, hell, use tank shock.
For the rest of your army comp... I don't know. A combat squad of scorpions or banshees or something, throw em in one of the falcons. Guardian squads with SCs or rangers. Avatar would probably be good, maybe a warwalker hulled down with starcannons. That or a prism cannon (guided) for long range marine death, and another skimmer-tank for him to worry about.
Wasp
