Sliver Overlord

{3}: Search your library for a Sliver card, reveal that card, put it into your hand, then shuffle.
{3}: Gain control of target Sliver. (This effect lasts indefinitely.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Sliver Hivelord

Sliver creatures you control have indestructible. (Damage and effects that say "destroy" don't destroy them.)

Crypt Sliver

All Slivers have "{T}: Regenerate target Sliver."

Island

Harmonic Sliver

All Slivers have "When this permanent enters, destroy target artifact or enchantment."

Forest

Sliver Queen

{2}: Create a 1/1 colorless Sliver creature token.

Sliver Legion

All Sliver creatures get +1/+1 for each other Sliver on the battlefield.

Thrumming Hivepool

Affinity for Slivers (This spell costs {1} less to cast for each Sliver you control.)
Slivers you control have double strike and haste.
At the beginning of your upkeep, create two 1/1 colorless Sliver creature tokens.

Sol Ring

Swamp

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Plains

Mountain

Command Tower

The First Sliver

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Sliver spells you cast have cascade.