Harry vs cavalry

Cavalry charges are all about momentum. You get a ton of furious horse and warrior going in one direction and flatten everything in your way. As the Sidhe cavalry came thundering toward us along the banks of the river, and as my heart pounded in my chest and my legs started shaking in naked fear, I knew that if I wanted to survive the next few seconds, I had to find a way to steal that momentum and use it for myself.
I dropped my blasting rod to grip my staff in both hand, and extend it before me. The moment I did, Sidhe riders began making swift warding gestures, accompanied by staccato bursts of magical pressure, separate protective charms rising up before each of them to block whatever magic I was about to throw.
The horses, however, didn't do any such thing.
I raised a shield, but not in a wall in front of me. Such a warding would have brought the faerie nobles into contact with it, and no one wizard could hold a spell against the wills of a score of faerie lords. I brought up a shield only a couple of feet high, and stretched it in a ribbon across the ground at the feet of Slate's mount.
The Winter Knight's steed, a giant grey-green beast, never knew what hit it. The low wall I'd called up clipped it at the knees, and it came crashing down to the misty earth with a scream, dragging Slate down with it. Talos, on Slate's right, could not react in time to stop his mount or to avoid the wall, but he threw himself clear as his horse went down, dropped into a roll as nimble and precise as any martial arts movie aficionado could desire, and came up on his feet. He spun, a dance-like step somehow in time with the vast song of the battlefield, and his sword came whipping at my head.
Dimly, I heard other horses screaming, tripping not only on my wall but on one another now, but I had no idea how well the spell had worked on the rest of the Sidhe warriors. I was too busy ducking Talos's first swing and backing out of range of the next.


Summer Knight Chapter 32, Page 354-355