Counterspell

Dregscape Sliver

Each Sliver creature card in your graveyard has unearth {2}.
Unearth {2} ({2}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Arcane Signet

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

Regal Sliver

Sliver creatures you control have "When this creature enters, Slivers you control get +1/+1 until end of turn if you're the monarch. Otherwise, you become the monarch."

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Heartstone

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Shifting Sliver

Slivers can't be blocked except by Slivers.

Manaweft Sliver

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

Megantic Sliver

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Bonescythe Sliver

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

Sliver Gravemother

The "legend rule" doesn't apply to Slivers you control.
Each Sliver creature card in your graveyard has encore {X}, where X is its mana value.
Encore {5} ({5}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Hatchery Sliver

Replicate {1}{G} (When you cast this spell, copy it for each time you paid its replicate cost.)
Each Sliver spell you cast has replicate. The replicate cost is equal to its mana cost. (A copy of a permanent spell becomes a token.)

Lavabelly Sliver

Sliver creatures you control have "When this creature enters, it deals 1 damage to target player or planeswalker and you gain 1 life."

Muscle Sliver

Harmonic Sliver

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

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Patriarch's Bidding

Each player chooses a creature type. Each player returns all creature cards of a type chosen this way from their graveyard to the battlefield.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Kindred Discovery

As this enchantment enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Sliver Hive

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a Sliver spell.
{5}, {T}: Create a 1/1 colorless Sliver creature token. Activate only if you control a Sliver.

Hibernation Sliver

All Slivers have "Pay 2 life: Return this permanent to its owner's hand."

Lazotep Sliver

Sliver creatures you control have afflict 2. (Whenever a creature with afflict 2 becomes blocked, defending player loses 2 life.)
Whenever a nontoken Sliver you control dies, amass Slivers 2. (Put two +1/+1 counters on an Army you control. It's also a Sliver. If you don't control an Army, create a 0/0 black Sliver Army creature token first.)

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.)

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.)

Forest

Ashnod's Altar

Plains

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Urza's Incubator

As this artifact enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Sliver Legion

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

Quick Sliver

Flash
Any player may cast Sliver spells as though they had flash.

Unclaimed Territory

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.

Constricting Sliver

Sliver creatures you control have "When this creature enters, you may exile target creature an opponent controls until this creature leaves the battlefield."

Sol Ring

Cavern of Souls

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Pulmonic Sliver

All Sliver creatures have flying.
All Slivers have "If this permanent would be put into a graveyard, you may put it on top of its owner's library instead."

Mana Echoes

Whenever a creature enters, you may add an amount of {C} equal to the number of creatures you control that share a creature type with it.

Sliver Hivelord

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

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.

Basal Sliver

All Slivers have "Sacrifice this permanent: Add {B}{B}."

Crystalline Sliver

All Slivers have shroud. (They can't be the targets of spells or abilities.)

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.)

Swamp

Syphon Sliver

Sliver creatures you control have lifelink. (Damage dealt by a Sliver creature you control also causes you to gain that much life.)

Island

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.

Necrotic Sliver

All Slivers have "{3}, Sacrifice this permanent: Destroy target permanent."

Kindred Dominance

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Sliver Queen

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

Three Tree City

As Three Tree City enters, choose a creature type.
{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.

Command Tower

Mountain

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.

Secluded Courtyard

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

Taunting Sliver

Sliver creatures you control have "When this creature enters, goad target creature an opponent controls." (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)