Fear of Change, a 2-drop Simic creature from Alchemy: Duskmourn
This five-cost sorcery destorys all dorks and artifacts, but keeps the rest around
Decks like The Wise MothmanThe Wise Mothman, Captain N'ghathrodCaptain N'ghathrod, and The MindskinnerThe Mindskinner will want The Water CrystalThe Water Crystal the most, as it turbo charges their milling shenanigans quite a bit
Some cards that I think could build out this shell: Ugin, Eye of the Storm Summon: Bahamut Solemn Simulacrum Adventurer's Inn The Irencrag Sire of Seven Deaths Mazemind Tome Fountainport Jill, Shiva's Dominant & Joshua, Phoenix's Dominant Jill and Joshua are two cards that feel powerful enough in Standard, that feel like they slot into a number of already existing archetypes
As chance would have it, Banzai works well as both a challenger and a quester
In a two-player game, Secret Rendezvous is worse than playing no card at all, but in a four-player game, its a great way to start an alliance to join up against a common enemy