Cast Singularity Rapture by paying ({3} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) , destroying all creatures and then causing any number of target players to mill a number of cards equal to half their library, rounded down, times two.
Notes
If a player has an odd number of cards in their library, they will have one card remaining. If they have an even number, they will have zero.