Heart Sliver

Morophon, the Boundless

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

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.

Cautery Sliver

All Slivers have "{1}, Sacrifice this permanent: This permanent deals 1 damage to any target."
All Slivers have "{1}, Sacrifice this permanent: Prevent the next 1 damage that would be dealt to target player, planeswalker, or Sliver creature this turn."

Crypt Sliver

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

Plated Sliver

Striking Sliver

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

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Sliver Legion

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

Sliver Hivelord

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

Crystalline Sliver

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

Hibernation Sliver

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

Eladamri's Call

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

Darkheart Sliver

All Slivers have "Sacrifice this permanent: You gain 3 life."

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

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.)

Screeching Sliver

All Slivers have "{T}: Target player mills a card."

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Necrotic Sliver

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

Basal Sliver

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

Quick Sliver

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

Sidewinder Sliver

All Sliver creatures have flanking. (Whenever a creature without flanking blocks a Sliver, the blocking creature gets -1/-1 until end of turn.)

Green Sun's Zenith

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

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.

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.)

Manaweft Sliver

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

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.)