Oh, that's also a simple design
Imagine stealing an opponent's Sol Ring with Treasure Nabber and then eating it
Whenever we put a mechanic in all five colors, we like to subdivide what the mechanic can do to help colors play differently
Slither Wing's first attack is mainly used to stall and disrupt the opponent, as it discards the top card of the opponent's deck, which is useful when dealing with cards like Ciphermaniac's Codebreaking that can place specific cards on the top of the deck
Recouping part of the cost makes this more reasonable as a card that probably doesnt impact the board, though you can cascade immediately with the Treasure you generate
Each Set Booster contains a foil-etched legend or Background card, as well as another legend, another Background, a rare or mythic rare, a traditional foil, and two wildcards