Liberator, Urza's Battlethopter

Flash
Flying
You may cast colorless spells and artifact spells as though they had flash.
Whenever you cast a spell, if the amount of mana spent to cast that spell is greater than Liberator, Urza's Battlethopter's power, put a +1/+1 counter on Liberator.

Urza's Command

Choose two —
• Creatures you don't control get -2/-0 until end of turn.
• Create a tapped Powerstone token.
• Create a tapped 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."
• Scry 1, then draw a card.

Urza, Prince of Kroog

Artifact creatures you control get +2/+2.
{6}: Create a token that's a copy of target artifact you control, except it's a 1/1 Soldier creature in addition to its other types.

Explorer's Scope

Whenever equipped creature attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Karn, Scion of Urza

+1: Reveal the top two cards of your library. An opponent chooses one of them. Put that card into your hand and exile the other with a silver counter on it.
−1: Put a card you own with a silver counter on it from exile into your hand.
−2: Create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."

Urza's Chalice

Whenever a player casts an artifact spell, you may pay {1}. If you do, you gain 1 life.

Blade of the Bloodchief

Whenever a creature dies, put a +1/+1 counter on equipped creature. If equipped creature is a Vampire, put two +1/+1 counters on it instead.
Equip {1}

Urza's Filter

Multicolored spells cost {2} less to cast.

Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Arena

{3}, {T}: Tap target creature you control and target creature of an opponent's choice they control. Those creatures fight each other. (Each deals damage equal to its power to the other.)

Urza, Powerstone Prodigy

Vigilance
{1}, {T}: Draw a card, then discard a card.
Whenever you discard one or more artifact cards, create a tapped Powerstone token. This ability triggers only once each turn. (The token is an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Urza's Incubator

As Urza's Incubator enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Urza's Armor

If a source would deal damage to you, prevent 1 of that damage.

Urza's Blueprints

Echo {6} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
{T}: Draw a card.

Brass Knuckles

When you cast this spell, copy it. (The copy becomes a token.)
Equipped creature has double strike as long as two or more Equipment are attached to it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Urza, Planeswalker

You may activate the loyalty abilities of Urza, Planeswalker twice each turn rather than only once.
+2: Artifact, instant, and sorcery spells you cast this turn cost {2} less to cast. You gain 2 life.
+1: Draw two cards, then discard a card.
0: Create two 1/1 colorless Soldier artifact creature tokens.
−3: Exile target nonland permanent.
−10: Artifacts and planeswalkers you control gain indestructible until end of turn. Destroy all nonland permanents.

Urza's Bauble

{T}, Sacrifice Urza's Bauble: Look at a card at random in target player's hand. You draw a card at the beginning of the next turn's upkeep.

Urza, Chief Artificer

Affinity for artifact creatures (This spell costs {1} less to cast for each artifact creature you control.)
Artifact creatures you control have menace.
At the beginning of your end step, create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."

Rath's Edge

{T}: Add {C}.
{4}, {T}, Sacrifice a land: Rath's Edge deals 1 damage to any target.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Urza, Lord High Artificer

When Urza, Lord High Artificer enters, create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."
Tap an untapped artifact you control: Add {U}.
{5}: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost.

Glasses of Urza

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Urza's Avenger

{0}: Urza's Avenger gets -1/-1 and gains your choice of banding, flying, first strike, or trample until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)

Urza's Ruinous Blast

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Exile all nonland permanents that aren't legendary.

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Urza's Miter

Whenever an artifact you control is put into a graveyard from the battlefield, if it wasn't sacrificed, you may pay {3}. If you do, draw a card.

Urza Assembles the Titans

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — Scry 4, then you may reveal the top card of your library. If a planeswalker card is revealed this way, put it into your hand.
II — You may put a planeswalker card with mana value 6 or less from your hand onto the battlefield.
III — You may activate the loyalty abilities of planeswalkers you control twice this turn rather than only once.

The Mightstone and Weakstone

When The Mightstone and Weakstone enters, choose one —
• Draw two cards.
• Target creature gets -5/-5 until end of turn.
{T}: Add {C}{C}. This mana can't be spent to cast nonartifact spells.
(Melds with Urza, Lord Protector.)

Urza, Lord Protector

Artifact, instant, and sorcery spells you cast cost {1} less to cast.
{7}: If you both own and control Urza, Lord Protector and an artifact named The Mightstone and Weakstone, exile them, then meld them into Urza, Planeswalker. Activate only as a sorcery.

Urza's Factory

{T}: Add {C}.
{7}, {T}: Create a 2/2 colorless Assembly-Worker artifact creature token.

Urza's Engine

Trample
{3}: Urza's Engine gains banding until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)
{3}: Attacking creatures banded with Urza's Engine gain trample until end of turn.