Jeskai Infiltrator is a rare Creature — Human Monk card from Ugin's Fate (UGIN), collector number 36. Current market price: $0.57, TCGplayer market prices via Scryfall.
This creature can't be blocked as long as you control no other creatures. When this creature deals combat damage to a player, exile it and the top card of your library in a face-down pile, shuffle that pile, then manifest those cards. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)