Entropic Serenity

Each player mills until they have milled {x}
number of instants, sorceries, or a combination
of the two. Player then exiles instants and
sorceries milled this way.
If a player cannot mill, instants and sorceries
milled in this way are exiled, and all other
cards milled in this way this turn are returned
to player's library.
Player then shuffles their library.
Exile Entropic Serenity.