Shifting Sliver

Slivers can't be blocked except by Slivers.

Mistform Ultimus

Mistform Ultimus is every creature type (even if this card isn't on the battlefield).

Galerider Sliver

Sliver creatures you control have flying.

Mistform Sliver

All Slivers have "{1}: This permanent becomes the creature type of your choice in addition to its other types until end of turn."

Shadow Sliver

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

Synapse Sliver

Whenever a Sliver deals combat damage to a player, its controller may draw a card.

Scuttling Sliver

Sliver creatures you control have "{2}: Untap this creature."

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}.

Psionic Sliver

All Sliver creatures have "{T}: This creature deals 2 damage to any target and 3 damage to itself."