Others have resisted the horse invasion, inventing cards like 'Horseocalypse', an artifact that can trivially exile all horses, 'Sparricus the Unhorse', a Kirin that synergizes with non-horse creatures, or 'Ketamine', a joke artefact that certainly works in the horse deck but feels rather against the spirit of the thing
You'll die as a state-based action when you do this unless you have a card like Phyrexian Unlife or Angel's Grace

Aberrant Aether Channeler Agent of Treachery Alquist Proft, Master Sleuth Architects of Will Armorcraft Judge Azor, the Lawbringer Baleful Strix Barbed Servitor Barrin, Tolarian Archmage Battlewing Mystic Bazaar Trademage Be'lakor, the Dark Master Beastbond Outcaster Bedlam Reveler Biomechan Engineer Blade Juggler Bladecoil Serpent Blood Servitor Bloodcrazed Socialite Bloodtithe Harvester Bonny Pall, Clearcutter Bookwurm Borborygmos and Fblthp Briarbridge Tracker Broodlord Caldaia Strongarm Callous Bloodmage Carnage Interpreter Carven Caryatid Cavalier of Flame Cavalier of Gales Cephalid Sage Champion of Dusk Champion of Wits Charming Scoundrel Chronicler of Heroes Circuit Mender Citanul Woodreaders Clackbridge Troll Clattering Augur Clive, Ifrit's Dominant Clockwork Servant Cloud of Faeries Cloudblazer Cloudkin Seer Combat Thresher Combustible Gearhulk Common Iguana Conciliator's Duelist Coralhelm Chronicler Crackling Drake Crypt Lurker Cultivator Colossus Didact Echo Discerning Peddler Disciple of Bolas Disciple of Freyalise Discourtesy Clerk Doom Weaver Dormant Sliver Drownyard Explorers Dusk Legion Zealot Duskana, the Rage Mother Eagle of Deliverance Earthshaker Dreadmaw Echo Inspector Echo of Death's Wail Elite Guardmage Elite Instructor Elvish Visionary Errand-Rider of Gondor

If you really want to optimize your collection, you should wait until the end of the event and choose the pack with the most unowned cards
Its even seen solid play in Modern from time to time, and was a go-to win condition in Legacy storm decks during the early days of the format
This record-breaking sale highlights how valuable this card has become