21 cards where the card types include “horse” and it’s legal in Historic

A-Cobbled Lancer (Innistrad: Crimson Vow #A-52)
A-Cosmos Charger (Kaldheim #A-51)
Bill the Pony (The Lord of the Rings: Tales of Middle-earth #3)
Breaching Hippocamp (Theros #43)
Calamity, Galloping Inferno (Outlaws of Thunder Junction #116)
Caustic Bronco (Outlaws of Thunder Junction #82)
Crested Sunmare (Hour of Devastation #6)
Diamond Mare (Core Set 2019 #231)
Dusk Charger (Rivals of Ixalan #69)
Lightning Mare (Core Set 2019 #151)
Nightmare (Welcome Deck 2017 #17)
Phyrexian Warhorse (Dominaria United #101)
Plague Mare (Core Set 2019 #114)
Shadowfax, Lord of Horses (The Lord of the Rings: Tales of Middle-earth #227)
Shield Mare (Core Set 2019 #37)
Surge Mare (Core Set 2019 #77)
Temur Charger (Khans of Tarkir #153)
Underworld Charger (Theros Beyond Death #120)
Vine Mare (Core Set 2019 #207)
Wandermare (Throne of Eldraine #204)
Wavebreak Hippocamp (Theros Beyond Death #80)

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