How to beat Eldar with Chaos Space Marines

Honestly i'm a bit lost. The Eldar army is hard as nuts. I still havn't cracked them. Nurgleprototype has a particularly large Eldar force that covers all sorts of different builds. They are nasty shooty, very fast and super hard to shift..... The Forces of Vantraxx the Thrice Cursed have been repelled time and time again but there is a new plan... An alliance... Necrosius and his Zombies. Lots and lots of Zombies....

Vantraxx the Thrice Cursed P-)