Invoke the Firemind

Etrata can't be blocked. Whenever Etrata deals combat damage to a player, exile target creature that player controls and put a hit counter on that card. That player loses the game if they own three or more exiled cards with hit counters on them. Etrata's owner shuffles Etrata into their library.

Create a token that's a copy of target artifact or creature. Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Counter target spell unless its controller pays X. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Look at the top three cards of your library. Put one of those cards into your hand, one on top of your library, and one on the bottom of your library.

Target creature gets -3/-3 until end of turn.

When this creature enters, each opponent loses 1 life for each creature they control. Transmute 1BB (1BB, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Ribbons of Night deals 4 damage to target creature and you gain 4 life. If U was spent to cast this spell, draw a card.

Create a 1/1 blue and black Horror creature token with flying. Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)