Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Counterspell

Heart Sliver

Plains

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Blur Sliver

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

Hive Stirrings

Create two 1/1 colorless Sliver creature tokens.

Hunter Sliver

All Sliver creatures have provoke. (Whenever a Sliver attacks, its controller may have target creature defending player controls untap and block it if able.)

Sea of Clouds

Sea of Clouds enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Arcane Signet

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

Shared Animosity

Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

Two-Headed Sliver

All Sliver creatures have menace. (They can't be blocked except by two or more creatures.)

Belligerent Sliver

Sliver creatures you control have menace. (They can't be blocked except by two or more creatures.)

Essence Sliver

Whenever a Sliver deals damage, its controller gains that much life.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

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}.

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Sliversmith

{1}, {T}, Discard a card: Create a 1/1 colorless Sliver artifact creature token named Metallic Sliver.

Opaline Sliver

All Slivers have "Whenever this permanent becomes the target of a spell an opponent controls, you may draw a card."

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Clifftop Retreat

Clifftop Retreat enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

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.

Shifting Sliver

Slivers can't be blocked except by Slivers.

Supreme Verdict

This spell can't be countered.
Destroy all creatures.

Stroke of Midnight

Destroy target nonland permanent. Its controller creates a 1/1 white Human creature token.

Weathered Wayfarer

{W}, {T}: Search your library for a land card, reveal it, put it into your hand, then shuffle. Activate only if an opponent controls more lands than you.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Bonesplitter Sliver

Homing Sliver

Each Sliver card in each player's hand has slivercycling {3}.
Slivercycling {3} ({3}, Discard this card: Search your library for a Sliver card, reveal it, put it into your hand, then shuffle.)

Bonescythe Sliver

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

Sinew Sliver

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Sentinel Sliver

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

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.

Spiteful Sliver

Sliver creatures you control have "Whenever this creature is dealt damage, it deals that much damage to target player or planeswalker."

Blade Sliver

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

Metallic Sliver

Swords to Plowshares

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

And They Shall Know No Fear

Choose a creature type. Creatures you control of the chosen type get +1/+0 and gain indestructible until end of turn.

Raka Disciple

{W}, {T}: Prevent the next 1 damage that would be dealt to any target this turn.
{U}, {T}: Target creature gains flying until end of turn.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters, you may pay 2 life. If you don't, it enters tapped.

Talon Sliver

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Galerider Sliver

Sliver creatures you control have flying.

Crystalline Sliver

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

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Harsh Mercy

Each player chooses a creature type. Destroy all creatures that aren't of a type chosen this way. They can't be regenerated.

Magma Sliver

All Slivers have "{T}: Target Sliver creature gets +X/+0 until end of turn, where X is the number of Slivers on the battlefield."

Winged Sliver

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Striking Sliver

Sliver creatures you control have first strike. (They deal combat damage before creatures without first strike.)

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Pillar of Origins

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

Cleaving Sliver

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."

Mountain

Island

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

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.)

Chromatic Lantern

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