Magic Theme Boosters are booster packs targeted at deckbuilding players, providing a number of cards from a certain expansion set that can go straight into their deck
Razormane Masticore, Molten-Tail Masticore, and Rotting Regisaur would later on play in this same space
Many cats enable a lifegain strategy, and Felidar Sovereign is a cat
Normally, The Sixth Doctor costs a bit of mana to cast, but with Amazing Spider-Man, you can get The Sixth Doctor down on the battlefield for only three mana, letting you take advantage of its effect during the early stages of the game
If you are attending a Quarter Century Stampede Release Celebration that is hosted as a Remote Duel event, you must have a valid shipping address in the country (United States or Canada) in which the Remote Duel Quarter Century Stampede Release Celebration event is being held in order to participate in that specific Remote Duel Quarter Century Stampede Release Celebration
The card has such widespread applications that even listing a single deck in particular to attribute it to feels like it misses the point