Ancient Ziggurat

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

Bonescythe Sliver

Sliver creatures you control have double strike. (They deal both first-strike and regular combat damage.)

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.

Crystalline Sliver

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

Muscle Sliver

Gemhide Sliver

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

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.

Predatory Sliver

Manaweft Sliver

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

Sinew Sliver

Sentinel Sliver

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

Cloudshredder Sliver

Sliver creatures you control have flying and haste.

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.

Galerider Sliver

Sliver creatures you control have flying.

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.