Urza, Lord High Artificer — ruling 1

The token created by Urza's first ability will count itself, so it'll be at least 1/1.

Urza, Lord High Artificer — ruling 2

You can tap any untapped artifact you control to pay the cost of the mana ability, including an artifact creature you haven't controlled continuously since the beginning of your most recent turn. Tapping an Equipment this way won't affect its abilities or the equipped creature.

Urza, Lord High Artificer — ruling 3

If you don't play the card exiled with Urza's last ability, it remains in exile.

Urza, Lord High Artificer — ruling 4

Urza's last ability doesn't change when you can play the exiled card. For example, if you exile a sorcery card, you can cast it only during your main phase when the stack is empty. If you exile a land card, you can play it only during your main phase and only if you have an available land play remaining.

Urza, Lord High Artificer — ruling 5

If a spell has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

Urza, Lord High Artificer — ruling 6

If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, you must pay those to cast the card.

Urza, Lord High Artificer : règles, fonctionnement et interactions (MTG)

Urza, Lord High Artificer 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

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

How it works : Urza, Lord High Artificer

Original English text — Wizards of the Coast / Scryfall

#1December 8, 2022· Wizards of the Coast
The token created by Urza's first ability will count itself, so it'll be at least 1/1.
No other card is named in this ruling.
#2December 8, 2022· Wizards of the Coast
You can tap any untapped artifact you control to pay the cost of the mana ability, including an artifact creature you haven't controlled continuously since the beginning of your most recent turn. Tapping an Equipment this way won't affect its abilities or the equipped creature.
No other card is named in this ruling.
#3December 8, 2022· Wizards of the Coast
If you don't play the card exiled with Urza's last ability, it remains in exile.
No other card is named in this ruling.
#4December 8, 2022· Wizards of the Coast
Urza's last ability doesn't change when you can play the exiled card. For example, if you exile a sorcery card, you can cast it only during your main phase when the stack is empty. If you exile a land card, you can play it only during your main phase and only if you have an available land play remaining.
No other card is named in this ruling.
#5December 8, 2022· Wizards of the Coast
If a spell has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
No other card is named in this ruling.
#6December 8, 2022· Wizards of the Coast
If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the card has any mandatory additional costs, you must pay those to cast the card.
No other card is named in this ruling.