Kain Darkwind's Savage Tide
The Horseman is a ghostly rider who prowled the jungle around Ossington, attacking those who attempted to break the fae siege of the town. Although initially he came into conflict with the party, he was later revealed to be a paladin of Tyr who had been murdered by Ysdon and Tully in retaliation for foiling their theft of The Jade Serpent.
The party discovered the Horseman’s mortal remains in the tarn under Red Horse Hill, along with the Jade Serpent, which had been concealed by the Horseman’s runic magic. Einar and Rath built him a makeshift cairn, leaving the entry open so that his spirit could still ride out.
The party joined forces with the Horsemen and the fae to recover the Jade Serpent and put an end to their plots. The Horseman was last seen dragging Ysdon off to justice.