These are available in Welcome Decks, Collector boosters, and the Marvels Spider-Man Eternal Spider-Man Scene Box only, which limits their supply (and raises their price tag, too!)
Rare Utility Land Cycle These lands are fairly easy to include in 2- and 3-color decks without downside, and once you start activating their abilities, its value town
Hangarback Walker is a great card, and its obviously best when you have ways to sacrifice it
Some cards like Turn to Slag, Fires of Mount Doom or Molten Rebuke destroy equipment attached to creatures they kill, but thats an effect of that card
In most games, resetting a single players board is all thats needed to keep things from getting out of hand
You may find this to be a difficult task, however, as there are many more cards that feel like upgrades than cards that you'll actually want to replace, forcing you to choose which ones you want to make room for