Plains

Ancient Ziggurat

{T}: Add one mana of any color. Spend this mana only to cast a creature spell.

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.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Unclaimed Territory

As Unclaimed Territory 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.

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.

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

Mutavault

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

Sinew Sliver

Galerider Sliver

Sliver creatures you control have flying.

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.

Shadow Sliver

All Sliver creatures have shadow. (They can block or be blocked by only creatures with shadow.)

Predatory Sliver

Necrotic Sliver

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

Harmonic Sliver

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

Two-Headed Sliver

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