Urza, Lord Protector — ruling 1

Urza, Lord Protector's first ability can't reduce the colored mana costs of spells you cast.

Urza, Lord Protector — ruling 2

During each of your turns, you may activate Urza, Planeswalker's loyalty abilities twice, whether that's activating the same ability two times, or activating two different abilities once each.

Urza, Lord Protector — ruling 3

When a pair of cards are melded, the result is a single creature that's represented by two cards. If the melded creature dies, both cards are put into your graveyard. As it leaves the battlefield, both of those cards are turned face up again. If the cards are put on the top or bottom of your library, you choose their relative order.

Urza, Lord Protector — ruling 4

One card in each pair of meld cards has an ability that instructs you to exile the two cards and meld them. If you control more than one object with one of those names, you select one object with that name to exile.

Urza, Lord Protector — ruling 5

When two cards are exiled and melded, they each leave the battlefield, then return together as one new object with no relation to either of the objects that left the battlefield. Counters, Auras, Equipment, and other effects that affected those two cards don't affect the melded permanent.

Urza, Lord Protector — ruling 6

Only two cards belonging to the same meld pair can be melded. Tokens, cards that aren't meld cards, or meld cards that don't form a meld pair can't be melded. If an effect instructs a player to meld cards that can't be melded, those cards remain in exile.

Urza, Lord Protector — ruling 7

While a meld card is in any zone other than the battlefield, it has only the characteristics of its front face. The same is true while it's on the battlefield with its front face up.

Urza, Lord Protector — ruling 8

While a melded permanent is on the battlefield, it has only the characteristics of its combined back face. Any effects that modify how the new object enters the battlefield will consider only the combined back face.

Urza, Lord Protector : règles, fonctionnement et interactions (MTG)

Urza, Lord Protector is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Artifact, instant, and sorcery spells you cast cost less to cast. : 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.

How it works : Urza, Lord Protector

Original English text — Wizards of the Coast / Scryfall

#1October 14, 2022· Wizards of the Coast
Urza, Lord Protector's first ability can't reduce the colored mana costs of spells you cast.
No other card is named in this ruling.
#2October 14, 2022· Wizards of the Coast
During each of your turns, you may activate Urza, Planeswalker's loyalty abilities twice, whether that's activating the same ability two times, or activating two different abilities once each.
Card named in this ruling
Urza, Planeswalker
#3October 14, 2022· Wizards of the Coast
When a pair of cards are melded, the result is a single creature that's represented by two cards. If the melded creature dies, both cards are put into your graveyard. As it leaves the battlefield, both of those cards are turned face up again. If the cards are put on the top or bottom of your library, you choose their relative order.
No other card is named in this ruling.
#4October 14, 2022· Wizards of the Coast
One card in each pair of meld cards has an ability that instructs you to exile the two cards and meld them. If you control more than one object with one of those names, you select one object with that name to exile.
No other card is named in this ruling.
#5October 14, 2022· Wizards of the Coast
When two cards are exiled and melded, they each leave the battlefield, then return together as one new object with no relation to either of the objects that left the battlefield. Counters, Auras, Equipment, and other effects that affected those two cards don't affect the melded permanent.
No other card is named in this ruling.
#6October 14, 2022· Wizards of the Coast
Only two cards belonging to the same meld pair can be melded. Tokens, cards that aren't meld cards, or meld cards that don't form a meld pair can't be melded. If an effect instructs a player to meld cards that can't be melded, those cards remain in exile.
No other card is named in this ruling.
#7October 14, 2022· Wizards of the Coast
While a meld card is in any zone other than the battlefield, it has only the characteristics of its front face. The same is true while it's on the battlefield with its front face up.
No other card is named in this ruling.
#8October 14, 2022· Wizards of the Coast
While a melded permanent is on the battlefield, it has only the characteristics of its combined back face. Any effects that modify how the new object enters the battlefield will consider only the combined back face.
No other card is named in this ruling.
#9October 14, 2022· Wizards of the Coast
Note that the permanent represented by the combined back faces has a color indicator.
No other card is named in this ruling.
#10October 14, 2022· Wizards of the Coast
The mana value of a melded permanent is the sum of the mana values of its front faces. A creature that becomes a copy of a melded permanent has only the characteristics of that combined back face, and its mana value is 0.
No other card is named in this ruling.
#11October 14, 2022· Wizards of the Coast
A player prompted to name a card may name the combined back face, and each player has the right to know that combined back face's characteristics at all times.
No other card is named in this ruling.
#12October 14, 2022· Wizards of the Coast
If an effect moves a melded permanent to a new zone and then affects "that card," it affects both cards.
No other card is named in this ruling.
#13October 14, 2022· Wizards of the Coast
In the Commander variant, a meld card's color identity is determined only by the mana costs and mana symbols in the rules text of its front face. No symbols or rules text of the permanent it melds into are considered.
No other card is named in this ruling.