Gitaxian Probe

• WWizards of the Coast2011-06-01
  Official Ruling
  To calculate the mana value of a card with Phyrexian mana symbols in its cost, count each Phyrexian mana symbol as 1.
• WWizards of the Coast2011-06-01
  Official Ruling
  The targeted player may have no cards in their hand. You'll still draw a card.
• WWizards of the Coast2011-06-01
  Official Ruling
  Phyrexian mana is not a new color. Players can't produce Phyrexian mana.
• WWizards of the Coast2011-06-01
  Official Ruling
  If you're at 1 life or less, you can't pay 2 life.
• WWizards of the Coast2011-06-01
  Official Ruling
  A card with Phyrexian mana symbols in its mana cost is each color that appears in that mana cost, regardless of how that cost may have been paid.
• WWizards of the Coast2011-06-01
  Official Ruling
  As you cast a spell or activate an activated ability with one or more Phyrexian mana symbols in its cost, you choose how to pay for each Phyrexian mana symbol at the same time you would choose modes or choose a value for X.

Rulings via Scryfall

• WO
  Wizards of the Coast2019-05-20

  Gitaxian Probe was banned in pauper on May 20, 2019. Gush and Gitaxian Probe allow decks to play fewer lands and replace them with spells, increasing the effectiveness of Augur of Bolas and Delver of Secrets. Daze and Gitaxian Probe tend to lead to less interactive gameplay, fewer shields-down moments, and less bluffing. Therefore, in order to weaken blue tempo decks without impacting the core cantrip-plus-Delver of Secrets gameplay, we are banning Gush, Daze, and Gitaxian Probe in Pauper. Source: https://magic.wizards.com/en/news/news/may-20-2019-banned-and-restricted-announcement
• WO
  Wizards of the Coast2018-07-02

  Gitaxian Probe was banned in legacy on July 2, 2018. Gitaxian Probe is a subtle but powerful card that has previously been banned in Modern and restricted in Vintage. Gitaxian Probe adds significant power to these decks and others by quickly filling the graveyard and counting toward abilities that require casting spells or drawing cards, without requiring mana investment. Because of the negative influence Gitaxian Probe has on gameplay as a free spell and low-cost information advantage, we prefer to remove it from the format rather than needing to weaken the strategies it facilitates in other ways. Source: https://magic.wizards.com/en/news/news/july-2-2018-banned-and-restricted-update-2018-07-02
• WO
  Wizards of the Coast2017-04-24

  Gitaxian Probe was restricted in vintage on April 24, 2017. The primary issue seems to revolve around the prevalence of free draw spells for the Mentor deck that let it churn through its library for no mana while creating an abundance of tokens. We believe by removing these free draw spells—and the perfect information that comes with Gitaxian Probe—we will significantly weaken Monastery Mentor–based strategies. Source: https://magic.wizards.com/en/news/news/april-24-2017-banned-and-restricted-announcement-2017-04-24