Im not a huge fan of giving my opponents anything good, but the costs to +1/+1 counter decks might get overbearing
Flavor Text "He that blows this horn shall set fear in the hearts of his enemies and joy in the hearts of his friends." owyn Number 241 Language English Legal Formats Commander, Historic, Legacy, Modern, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Pauper, Pioneer, Standard, Timeless Rulings (6/16/2023) Two or more creatures you control must attack the same player in order for Horn of the Mark's ability to trigger
Card sleeves are like mini-shields for your cards
banish it (until their next Standby Phase), and if you do, any monsters they currently control lose 1000 ATK until the end of this turn