The Ur-Dragon

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

Underground Sea

Ancestral Recall

Ankh of Mishra

Whenever a land enters, this artifact deals 2 damage to that land's controller.

Taiga

Counterspell

Balance

Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.

Sol Ring

Savannah

Mox Pearl

Cavern of Souls

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, and that spell can't be countered.

Mox Sapphire

Mox Ruby

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, this artifact deals 3 damage to you.
{T}: Add {C}{C}.

Plateau

Time Walk

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Mountain

Badlands

Black Lotus

{T}, Sacrifice this artifact: Add three mana of any one color.

Scrubland

Copy Artifact

You may have this enchantment enter as a copy of any artifact on the battlefield, except it's an enchantment in addition to its other types.

Timetwister

Each player shuffles their hand and graveyard into their library, then draws seven cards. (Then put Timetwister into its owner's graveyard.)

Tropical Island

Bayou

Time Vault

This artifact enters tapped.
This artifact doesn't untap during your untap step.
If you would begin your turn while this artifact is tapped, you may skip that turn instead. If you do, untap this artifact.
{T}: Take an extra turn after this one.