Synapse Sliver

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

Virulent Sliver

All Sliver creatures have poisonous 1. (Whenever a Sliver deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)

Arcane Signet

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

Shifting Sliver

Slivers can't be blocked except by Slivers.

Arcane Sanctum

This land enters tapped.
{T}: Add {W}, {U}, or {B}.

Mountain

Muscle Sliver

Forest

Might Sliver

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Counterspell

Blur Sliver

Sliver creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Bonescythe Sliver

Sliver creatures you control have double strike. (They deal both first-strike and regular combat damage.)

Harmonic Sliver

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

Sliver Hivelord

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

Island

Manaweft Sliver

Sliver creatures you control have "{T}: Add one mana of any color."

Negate

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon enters, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Venom Sliver

Sliver creatures you control have deathtouch. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

Bonesplitter Sliver

Plains

Brood Sliver

Whenever a Sliver deals combat damage to a player, its controller may create a 1/1 colorless Sliver creature token.

Cleaving Sliver

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Swamp

Predatory Sliver

Tempered Sliver

Sliver creatures you control have "Whenever this creature deals combat damage to a player, put a +1/+1 counter on it."

Command Tower

Sentinel Sliver

Sliver creatures you control have vigilance. (Attacking doesn't cause them to tap.)