These new cards are what are known as heroes (casually referred to in R&D as the flip cards)
Mayhem and web-slinging were both mechanics we liked early on to demonstrate some of the top-down flavor of Spider-Man, which is why they stuck around so long despite the lessons we learned about Pick-Two Draft liking lower-synergy decks
artifact Archaeomancer's Map When this artifact enters, search your library for up to two basic Plains cards, reveal them, put them into your hand, then shuffle
The party mechanic fell flat when introduced in Zendikar Rising, and hasnt really gained in popularity since then
For Magic: The Gathering Compilation Sets (like Modern Masters, Dominaria Remastered, etc), the prices for Booster Boxes tend to be different from the core or expansion set boosters