Cavern of Souls

As Cavern of Souls 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.

Harmonic Sliver

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

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Sedge Sliver

All Sliver creatures have "This creature gets +1/+1 as long as you control a Swamp."
All Slivers have "{B}: Regenerate this permanent." (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Sinew Sliver

Changeling Outcast

Changeling (This card is every creature type.)
Changeling Outcast can't block and can't be blocked.

Sliver Legion

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

Selesnya Signet

City of Brass

Whenever City of Brass becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Shadow Sliver

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

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Arid Mesa

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Faeburrow Elder

Vigilance
Faeburrow Elder gets +1/+1 for each color among permanents you control.
{T}: For each color among permanents you control, add one mana of that color.

Opaline Sliver

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

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}.

Jegantha, the Wellspring

Companion — No card in your starting deck has more than one of the same mana symbol in its mana cost. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
{T}: Add {W}{U}{B}{R}{G}. This mana can't be spent to pay generic mana costs.

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.

Bonescythe Sliver

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

Marsh Flats

{T}, Pay 1 life, Sacrifice Marsh Flats: Search your library for a Plains or Swamp card, put it onto the battlefield, then shuffle.

Sliver Hivelord

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

Door of Destinies

As Door of Destinies enters, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.
Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.

Yisan, the Wanderer Bard

{2}{G}, {T}, Put a verse counter on Yisan, the Wanderer Bard: Search your library for a creature card with mana value equal to the number of verse counters on Yisan, put it onto the battlefield, then shuffle.

Scuttling Sliver

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

Misty Rainforest

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Bladeback Sliver

Hellbent — As long as you have no cards in hand, Sliver creatures you control have "{T}: This creature deals 1 damage to target player or planeswalker."

Mountain

Scalding Tarn

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Island

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.)

Hivestone

Creatures you control are Slivers in addition to their other creature types.

Galerider Sliver

Sliver creatures you control have flying.

Syphon Sliver

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

Hindering Light

Counter target spell that targets you or a permanent you control.
Draw a card.

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Verdant Catacombs

{T}, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

Forest

Essence Sliver

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

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless 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.

Bloodstained Mire

{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Etchings of the Chosen

As Etchings of the Chosen enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{1}, Sacrifice a creature of the chosen type: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Golgari Signet

Firewake Sliver

All Sliver creatures have haste.
All Slivers have "{1}, Sacrifice this permanent: Target Sliver creature gets +2/+2 until end of turn."

Slimefoot, the Stowaway

Whenever a Saproling you control dies, Slimefoot, the Stowaway deals 1 damage to each opponent and you gain 1 life.
{4}: Create a 1/1 green Saproling creature token.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Simic Signet

Striking Sliver

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

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

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.)

Biomancer's Familiar

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: The next time target creature adapts this turn, it adapts as though it had no +1/+1 counters on it.

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."

Bloom Tender

{T}: For each color among permanents you control, add one mana of that color.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

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.

Vanquisher's Banner

As Vanquisher's Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

Gruul Signet

Lose Focus

Replicate {U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Counter target spell unless its controller pays {2}.

Heroic Intervention

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

Plains

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Time of Need

Search your library for a legendary creature card, reveal it, put it into your hand, then shuffle.

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.)

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Swamp

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Beast Within

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

Predatory Sliver

Jodah, Archmage Eternal

Flying
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.

Reflections of Littjara

As Reflections of Littjara enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Sentinel Sliver

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

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Necrotic Sliver

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

Eladamri's Call

Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

Gemhide Sliver

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

Wooded Foothills

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, 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."

Windswept Heath

{T}, Pay 1 life, Sacrifice Windswept Heath: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Manaweft Sliver

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

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.

Cryptolith Rite

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

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Tempered Sliver

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