Keeper of the Accord is a rare Creature — Human Soldier card from Commander Legends Promos (PCMR), collector number 27p. Current market price: $1.82 (foil $4.39), TCGplayer market prices via Scryfall.
At the beginning of each opponent's end step, if that player controls more creatures than you, create a 1/1 white Soldier creature token. At the beginning of each opponent's end step, if that player controls more lands than you, you may search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.