Walker of Secret Ways is a uncommon Creature — Human Ninja card from Betrayers of Kamigawa (BOK), collector number 60. Current market price: $1.86 (foil $22.35), TCGplayer market prices via Scryfall.
Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever this creature deals combat damage to a player, look at that player's hand. {1}{U}: Return target Ninja you control to its owner's hand. Activate only during your turn.