The other day I faced a primarily Inquisition army, 750 points with an Imperial Knight detachment. The terrain somewhat played against my capacity to fight some of his ground forces, but the rest where relatively easy.
My plan was to rush in with a raider full of wyches and destroy the Imperial Knight with Haywire grenades. Terrain and tactics did not permit me a clear rush and in the end I never succeeded with the plan. However, even surrounding it to get some shots in on it's unbarriered side gave me some clear imagery of how powerful one of these units was in battle and how it forced tactical changes.
It forces the enemy to focus a good bit of forces on taking out the Knight or face unparalleled destructive power. In Melee it instant wounds when it wounds, and often can't be saved against. In range it has enough fire power to take down squads.
----so my question and input...
Is Imperial Knights a viable ally for Dark Eldar?
First I'm not too familiar with them. I've only seen one in use and I imagine there is not much hype about using them due to their price and points. But tactically it becomes the biggest target on the field. Enemies will fire at it, until it's down. How does this benefit us? Exactly by doing that thing.
I find most of the time my opponents target my raiders, or venoms before I can get them to safety or get them in range to deal the appropriate damage. This forces them to choose between a mobile and powerful threat, or a giant hard to kill powerful threat. Defending the Knight could also be done with relative ease, forcing your opponent to get behind it's shield to deal damage also could force them into positions where your dark eldar can take advantage of the move.
Meanwhile if they fire at your raiders and venoms first, or try to focus on them. They get an Imperial Knight coming down on them at a rather unreasonable strength. On top of this, if they try to split their focus between, (which in most game types with objectives they already are doing) either your weight of fire or dark lance weight of fire + their mobility on top of the big thing coming down on them may ruin enough of their forces quick enough to crush them.
Now this is just guessing of course. and Fluff wise it'd be fun to see a Dark Eldar style Imperial Knight. But... Thoughts? I'm seriously considering this.