The Seventh Doctor — ruling 1

To choose a card in your hand for The Seventh Doctor's ability, take a card in your hand and separate it from the others, face down. Then the defending player guesses whether the mana value of that card is greater than the number of artifacts you control. You do not have to reveal whether they guess right or wrong unless you are casting the card.

The Seventh Doctor — ruling 2

If the card you chose has an {X} in its mana cost, the value of X is 0.

The Seventh Doctor — ruling 3

Unlike other creature types in Magic that are each only one word, the two words "Time Lord" represent a single creature subtype. Time Lord is the only two-word creature type.

The Seventh Doctor — ruling 4

Neither "Time" nor "Lord" are creature types. Some older cards were printed with the subtype "Lord," but all of those cards have updated Oracle card text that removed that type.

The Seventh Doctor — ruling 5

If an effect instructs you to choose a creature type, you may choose Time Lord.

The Seventh Doctor : règles, fonctionnement et interactions (MTG)

The Seventh Doctor 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

Whenever The Seventh Doctor attacks, choose a card in your hand. Defending player guesses whether that card's mana value is greater than the number of artifacts you control. If they guessed wrong, you may cast it without paying its mana cost. If you don't cast a spell this way, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this token: Draw a card.")

How it works : The Seventh Doctor

Original English text — Wizards of the Coast / Scryfall

#1October 13, 2023· Wizards of the Coast
To choose a card in your hand for The Seventh Doctor's ability, take a card in your hand and separate it from the others, face down. Then the defending player guesses whether the mana value of that card is greater than the number of artifacts you control. You do not have to reveal whether they guess right or wrong unless you are casting the card.
No other card is named in this ruling.
#2October 13, 2023· Wizards of the Coast
If the card you chose has an in its mana cost, the value of X is 0.
No other card is named in this ruling.
#3October 13, 2023· Wizards of the Coast
Unlike other creature types in Magic that are each only one word, the two words "Time Lord" represent a single creature subtype. Time Lord is the only two-word creature type.
No other card is named in this ruling.
#4October 13, 2023· Wizards of the Coast
Neither "Time" nor "Lord" are creature types. Some older cards were printed with the subtype "Lord," but all of those cards have updated Oracle card text that removed that type.
No other card is named in this ruling.
#5October 13, 2023· Wizards of the Coast
If an effect instructs you to choose a creature type, you may choose Time Lord.
No other card is named in this ruling.