Doomsday Excruciator | Breach the Multiverse

Cards

Cast
Doomsday Excruciator by paying ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) .
When
Doomsday Excruciator enters the battlefield, it triggers, exiling all but the bottom six cards of each library face down.
Cast
Breach the Multiverse by paying ({5} magic symbol) ({B} magic symbol) ({B} magic symbol) , causing each player to mill ten cards, thus milling the remainder of each player's library.
When your opponents go to draw a card during their next draw steps, they will lose the game due to attempting to draw from an empty library.

This combo has been estimated to be Spicy (Bracket 3-4+).