Once again, going off artwork, game design, and knowledge of mechanics alone, Im hoping Emet is an Orzhov or Mardu creature with the ability to bring allies back from the graveyard or banish allies and then play them
Counter Intelligence feels very cohesive, as a whole from artwork to themes and mechanics
Two of blacks biggest strengths are creature destruction and card draw
I dont care about rarity, more about function
Here's how the deck looks with the upgrades added: Also to pre-emptively address some comments: one direction that you can take the upgrades is to really lean into Sliver Gravemother's encore ability and turn the deck into a straight-up Encore deck -- Buried Alive and Entomb cards to put slivers into your graveyard, Convergence of Dominion and Zirda, the Dawnwaker to make encore cost less (though PSA Training Grounds doesn't work, I see people suggesting it but sorry no), Mondrak, Glory Dominus to double the encore tokens, Sundial of the Infinite to keep the encore tokens permanently -- that sounds sweet and all but you'd need to do a massive rework of this entire precon, turning it from a Go Wide Sliver Combat deck to Sliver Reanimator essentially