Bartmoss, Demon Creator

When Bartmoss enters, choose any number of opponents
and choose a mode for each.
{x} is equal to the number of demons you control.
• Target player mills {x} cards.
• Target player sacrifices {x} creatures.
• Target player exiles {x} cards from their graveyard with a Virus Counter.
At the beginning of your end step, choose a creature card that was milled, exiled with a Virus Counter, or sacrificed, and return it to the battlefield under your control. The creature is a demon in additi