Brief CID scene in the idw comics. The mare is named raven, and I think is some sort of royal advisor. The context is that a spirit of one of discords old "friends" has started possessing bodies, including Luna, Twilight, and Celestia, and shut up some of the palace staff.
https://readcomiconline.to/Comic/My-Lit ... =151747#38
MLP issue 75
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