It includes buying singles, trading with other players, or using cards you already own
Sheoldreds backside is a problem for opponents that will ultimately put all creature cards in all graveyards onto the battlefield under your control
Thassa's Oracle has come to prominence as an alternate win condition in self-mill decks
Three mana to cheat into play one of your own creatures from the library to the battlefield would be excellent, but taking that creature from your opponent is incredibly slimy yet satisfying
Multicolor-Colorless Hybrids This cycle of cards is really interesting to me as they dont squarely force you to be in a specific 3-color clan, but place a value on cost vs ease of casting
Youre paying four mana, sure, but you immediately get three of that back, and then subsequently get that three every turn thereout