Rukarumel, Biologist

As Rukarumel, Biologist enters the battlefield, 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.

Striking Sliver

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

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.)

Crypt Sliver

All Slivers have "{T}: Regenerate target Sliver."

Manaweft Sliver

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

Sinew Sliver

Crystalline Sliver

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

Necrotic Sliver

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

Sentinel Sliver

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

Gemhide Sliver

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

Shifting Sliver

Slivers can't be blocked except by Slivers.

Quick Sliver

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

Sliver Hivelord

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

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

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 the battlefield, destroy target artifact or enchantment."

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}.

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.)

Two-Headed Sliver

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

Lavabelly Sliver

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

Blur Sliver

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