I had an idea of using a Noble Battle Standard Bearer on a Dark Steed, making him very mobile and play him along with multiple close combat units of Dark Riders... If the BSB has the Hydrabanner they can rake up a large number or wounds. The only problem is that it's all S4 & S3 attacks, so you can't hit too tough opponents. I had some luck with this tactic but it was not as good as I hoped. The Hydra heads come from a Warmaster Hydra.