Shadow Sliver

All Sliver creatures have shadow. (They can block or be blocked by only creatures with shadow.)

Serum Visions

Mesmeric Sliver

All Slivers have "When this permanent enters, you may fateseal 1." (To fateseal 1, its controller looks at the top card of an opponent's library, then they may put that card on the bottom of that library.)

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Screeching Sliver

All Slivers have "{T}: Target player mills a card."

Unsummon

Return target creature to its owner's hand.

Vapor Snag

Return target creature to its owner's hand. Its controller loses 1 life.

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Boomerang

Return target permanent to its owner's hand.

Island

Galerider Sliver

Sliver creatures you control have flying.

Eye of Nowhere

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.