Keleth is a mare from an unknown plane, and a familiar.
History
On the battlefield, a compatible mount can mean the difference between life and death. And if one wishes to ride Keleth, compatibility is everything. Known in some circles as "the Kingmaker," any knight accepted by Keleth is destined for glory in battle and beyond. However, when the dust settles and her rider claims their reward, Keleth vanishes—only to reappear on a different battlefield sometime after, searching for a new rider.