Hey guys! I like to run my campaigns to be more "real," for example: if the dark eldar are attacking a listening post that the PCs have to defend I don't want it to just be a set piece, I want there to be a reason the soldiers are attacking. Are they just wanting to flay guardsmen for downtime or are the drawing attention away from the bigger attack on the artillery line? Aside from EotI what battle strategies have you guys used on a grand scale?

Well if its a listening post it could be that they want to silence it so that they can attack their main targets undetected.

I've always imagined the that the dark eldar will attack in multiple swift and stealthy attacks, it could be that if this listening post is destroyed it would allow them to assault a HQ or hospital or similar, taking out a HQ or supply dump or similar would be a good move strategically (as it would limit organized resistance to attack and help them defeat the imperial forces piecemeal much more easily) while as dark eldar are vicious slavers who like to play mind games I could well imagine them prioritizing attacking a hospital or refugee camp as a horror attack/slave grab.

I agree with the guy above me. He posted something what you should normally do as a DM/GM and be creative as to why. Always ask yourself why when you decide the party is going to be attacked or a building. Dark Eldar are normally sneaky and fast attack so they dont attack just because but they attack for a reason. Also some more examples it can be a forward outpost where they call down artillery and if this falls vehicles might be able to brake threw. As a GM I always tie in battle attacks depending on the army. Orks attack randomly with random strength so in some cases I make a random table roll but in alot of cases I always tie in the attack with the story.

Well with works I like to add a warboss who knows what he's doing, and while most attack at random because of itchy trigger fingers he will take advantage and direct the rest of his forces accordingly (I'll give you 3 guesses as to which army I play on TT)