Unlocking the Enchiridion is a Weiß Schwarz card from Adventure Time AT/WX02-097. Compare listings from Singapore Weiß Schwarz sellers on CardJio, then jio them on WhatsApp.
Look at up to 4 cards from the top of your deck, choose up to 1 《Ooo》 character from among them, reveal it to your opponent, put it into your hand, and put the rest into your waiting room.