This is because the Delver is part of a mega cycle. In other words, cards spread across multiple sets are used to tell the story here
What is largely considered the worst of the early Magic sets: Homelands
Card Set(s) -CARRYING ON HIS WILL- [OP-13] CARD VIEW OP13-035 | C | CHARACTER Bepo Attribute Strike Block icon 4 Type Minks/FILM/Heart Pirates Effect [End of Your Turn] Set this Character or up to 1 of your DON
Say your opponent has played into a very strong win condition that has Flying and Ward, like Vein Ripper
P/T Set Number 201 Language Espaol Legal Formats Alchemy, Brawl, Commander, Competitive Brawl, Historic, Legacy, Modern, Pioneer, Standard, Timeless, Vintage Rulings (6/6/2025) Each face of a nonmodal double-faced card has its own set of characteristics: name, types, subtypes, abilities, and so on
This is where the infinite combo comes into play: as your lands are untapped again, you can repeat the process until you choose to stop