Cavern of Souls

As Cavern of Souls enters the battlefield, choose a creature type. {T}: Add {1} to your mana pool. {T}: Add one mana of any color to your mana pool. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Collected Company

Look at the top six cards of your library. Put up to two creature cards with converted mana cost 3 or less from among them onto the battlefield. Put the rest on the bottom of your library in any order.

Sentinel Sliver

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

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.)

Blur Sliver

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

Manaweft Sliver

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

Predatory Sliver

Sliver creatures you control get +1/+1.

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}.

Sliver Hive

{T}: Add {1} to your mana pool. {T}: Add one mana of any color to your mana pool. Spend this mana only to cast a Sliver spell. {5}, {T}: Put a 1/1 colorless Sliver creature token onto the battlefield. Activate this ability only if you control a Sliver.

Spellskite

{U/P}: Change a target of target spell or ability to Spellskite. ({U/P} can be paid with either {U} or 2 life.)

Sinew Sliver

All Slivers get +1/+1.

Necrotic Sliver

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

Mutavault

{T}: Add {1} to your mana pool. {1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Sedge Sliver

All Slivers have "This creature gets +1/+1 as long as you control a Swamp" and "{B}: Regenerate this creature."

Telekinetic Sliver

All Slivers have "{T}: Tap target permanent."

Overgrown Tomb

Verdant Catacombs

Watery Grave

Godless Shrine

({T}: Add {W} or {B}.) As Godless Shrine enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Forest

({T}: Add {G}.)