Not sleeving your Magic: The Gathering cards exposes them to scratches, dirt, bending, and other damage, which can significantly reduce their condition and value especially for rare or collectible cards
Furthermore, this card is also incredibly frustrating to get rid of for the opponent because it can special summon itself from the GY by banishing a light and dark attribute monster from the hand or the GY
Cards that have a high playability factor in competitive decks often see a surge in value
for example, I didnt see any way to make a battle, double-faced card, or a traditional split card
This card, featuring Psyduck and Jigglypuff laying sleepily in a hammock in a tropical setting, has become a hobby icon and one of the most sought-after trainer cards