In an Orzhov shell, this card generates 2-for-1 trades constantly, allowing you to out-value ramp decks that rely on playing one big spell per turn
If you control no other creatures at that time, X is 0.
At each end step, Toxrill places a slime counter on every creature your opponents control, slowly wiping the board while creating a swarm of slugs
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
