Whatnot Whatnot is a little bit different than most platforms, and Ive never engaged with it myself, so Im a little wary to give it a full recommendation
Emry, Lurker of the Loch A bit of a unique contender to the list, Emry, Lurker of the Loch is a self-mill card used in blue/black Dimir decks, primarily focused on secrecy and underhanded deeds
Somehow, that doesn't seem fair
These one-mana creatures force their target to mill three cards any time a land enters the battlefield under your control
Plus, those six cards are new to Magic and different for each Scene Box, so across all four there's a total of 24 new-to- Magic cards
Esper has an Achilles heel where if youre playing cards that deal a lot of damage quickly, the control deck is unlikely to be able to match up their spells profitably