Triumph of the Hordes is a rare Sorcery card from Secret Lair Drop (SLD), collector number 2366. Current market price: $14.32 (foil $10.90), TCGplayer market prices via Scryfall.
Until end of turn, creatures you control get +1/+1 and gain trample and infect. (Creatures with infect deal damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)