Secluded Courtyard

As this land 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 or activate an ability of a creature source of the chosen type.

Mutavault

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

Galerider Sliver

Sliver creatures you control have flying.

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Island

Fiery Islet

{T}, Pay 1 life: Add {U} or {R}.
{1}, {T}, Sacrifice Fiery Islet: Draw a card.

Predatory Sliver

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}.

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.

Silent Clearing

{T}, Pay 1 life: Add {W} or {B}.
{1}, {T}, Sacrifice Silent Clearing: Draw a card.

Chalice of the Void

Chalice of the Void enters with X charge counters on it.
Whenever a player casts a spell with mana value equal to the number of charge counters on Chalice of the Void, counter that spell.

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 Hivelord

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

Leeching Sliver

Whenever a Sliver you control attacks, defending player loses 1 life.

Plains

Sinew Sliver

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.

Frenetic Sliver

All Slivers have "{0}: If this permanent is on the battlefield, flip a coin. If you win the flip, exile this permanent and return it to the battlefield under its owner's control at the beginning of the next end step. If you lose the flip, sacrifice it."

Aether Vial

At the beginning of your upkeep, you may put a charge counter on Aether Vial.
{T}: You may put a creature card with mana value equal to the number of charge counters on Aether Vial from your hand onto the battlefield.