39 cards where the full Oracle text includes “horsemanship”

Barbarian General (Portal Three Kingdoms #100)
Borrowing the East Wind (Portal Three Kingdoms #133)
Broken Dam (Portal Three Kingdoms #37)
Cao Ren, Wei Commander (Portal Three Kingdoms #69)
Guan Yu, Sainted Warrior (Masters Edition III #12)
Herald of Hoofbeats (March of the Machine Commander #22)
Lady Zhurong, Warrior Queen (Portal Three Kingdoms #139)
Liu Bei, Lord of Shu (Masters Edition III #19)
Lu Bu, Master-at-Arms (Masters Edition III #108)
Lu Meng, Wu General (Masters Edition III #41)
Lu Xun, Scholar General (Commander Anthology #41)
Ma Chao, Western Warrior (Portal Three Kingdoms #116)
Merry-Go-Round (Unfinity #222a)
Riding Red Hare (Portal Three Kingdoms #18)
Riding the Dilu Horse (Masters Edition III #131)
Rolling Earthquake (Double Masters #142)
Shu Cavalry (Masters Edition III #23)
Shu Elite Companions (Masters Edition III #24)
Shu General (Masters Edition III #25)
Sun Ce, Young Conquerer (Masters Edition III #52)
Sun Quan, Lord of Wu (Commander Masters #123)
Taoist Mystic (Portal Three Kingdoms #151)
The Girl in the Fireplace (Doctor Who #21)
Trip Wire (Masters Edition III #137)
Wei Elite Companions (Masters Edition III #79)
Wei Night Raiders (Masters Edition III #81)
Wei Scout (Portal Three Kingdoms #90)
Wei Strike Force (Masters Edition III #82)
Wu Elite Cavalry (Masters Edition III #54)
Wu Light Cavalry (Portal Three Kingdoms #60)
Wu Scout (Portal Three Kingdoms #62)
Xiahou Dun, the One-Eyed (Masters Edition III #83)
Yellow Scarves Cavalry (Portal Three Kingdoms #125)
Yellow Scarves General (Portal Three Kingdoms #126)
Yuan Shao, the Indecisive (Portal Three Kingdoms #128)
Zhang Fei, Fierce Warrior (Masters Edition III #28)
Zhang He, Wei General (Portal Three Kingdoms #95)
Zhao Zilong, Tiger General (Portal Three Kingdoms #33)
Zuo Ci, the Mocking Sage (Portal Three Kingdoms #165)

This search is finished. Now the real work can begin.