Sosuke, Son of Seshiro is a uncommon Legendary Creature — Snake Warrior card from Champions of Kamigawa (CHK), collector number 244. Current market price: $0.22 (foil $3.51), TCGplayer market prices via Scryfall.
Other Snake creatures you control get +1/+0. Whenever a Warrior you control deals combat damage to a creature, destroy that creature at end of combat.