However I did draw a hard line around cards which primarily serve to mill your entire deck into your graveyard in one go: Hermit Druid, Cephalid Illusionist, Balustrade Spy, and so on
In a four-player game, one will likely just have zero or one, so nothing will happen with that person, just like a Balance
Crystals The full colored cycle of Crystals reduce costs, and each one has a static ability and an activated ability, so the 4 mana value slot is a key one to launch you into the the biggest and strongest cards, and rely on 2-mana rocks to curve into these on turn 3
Blow the Whistle allows him to shut down opponent actions until the start of the player's next turn, potentially neutralizing powerful songs and more
Timeless is Magic: The Gathering Arena's fully eternal format