Rukarumel, Biologist

As Rukarumel, Biologist enters, choose a creature type.
Slivers you control and nontoken creatures you control are the chosen type in addition to their other creature types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 1/1 colorless Sliver creature token.

Hive Stirrings

Create two 1/1 colorless Sliver creature tokens.

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.)

Hibernation Sliver

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

Two-Headed Sliver

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

Rocco, Cabaretti Caterer

When Rocco, Cabaretti Caterer enters, if you cast it, you may search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Brood Sliver

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

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.)

Sliver Legion

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

Timberwatch Elf

{T}: Target creature gets +X/+X until end of turn, where X is the number of Elves on the battlefield.

Commander's Sphere

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

Galerider Sliver

Sliver creatures you control have flying.

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.

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.

Elvish Promenade

Create a 1/1 green Elf Warrior creature token for each Elf you control.

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.)

Marwyn, the Nurturer

Whenever another Elf you control enters, put a +1/+1 counter on Marwyn, the Nurturer.
{T}: Add an amount of {G} equal to Marwyn's power.

Ezuri, Renegade Leader

{G}: Regenerate another target Elf.
{2}{G}{G}{G}: Elf creatures you control get +3/+3 and gain trample until end of turn.

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.)

Harmonic Sliver

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

Chromatic Lantern

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

Crystalline Sliver

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

Abomination of Llanowar

Vigilance; menace (This creature can't be blocked except by two or more creatures.)
Abomination of Llanowar's power and toughness are each equal to the number of Elves you control plus the number of Elf cards in your graveyard.

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Sentinel Sliver

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

Elvish Champion

Other Elf creatures get +1/+1 and have forestwalk. (They can't be blocked as long as defending player controls a Forest.)

Syphon Sliver

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

Winged Sliver

Chromatic Orrery

You may spend mana as though it were mana of any color.
{T}: Add {C}{C}{C}{C}{C}.
{5}, {T}: Draw a card for each color among permanents you control.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Wirewood Channeler

{T}: Add X mana of any one color, where X is the number of Elves on the battlefield.

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Lightning Greaves

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

Harald, King of Skemfar

Menace (This creature can't be blocked except by two or more creatures.)
When Harald, King of Skemfar enters, look at the top five cards of your library. You may reveal an Elf, Warrior, or Tyvar card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.