Gonti, Lord of Luxury

• WOTC Official Reminder Textofficial rules
  Deathtouch — Any amount of damage this deals to a creature is enough to destroy it.

• WWizards of the Coast2016-09-20
  Official Ruling
  Casting the card causes it to leave exile. You can't cast it multiple times.
• WWizards of the Coast2016-09-20
  Official Ruling
  If you leave the game, the card remains exiled face down indefinitely. No player may look at it.
• WWizards of the Coast2016-09-20
  Official Ruling
  You pay the costs for the exiled card if you cast it. You may pay alternative costs such as emerge rather than the card's mana cost.
• WWizards of the Coast2016-09-20
  Official Ruling
  An effect that instructs you to "cast" a card doesn't allow you to play lands.
• WWizards of the Coast2016-09-20
  Official Ruling
  You may look at and cast that card (and spend mana as though it were mana of any type to do so) even if Gonti leaves the battlefield. If another player gains control of Gonti, that player can't look at or cast the card, and you still can.
• WWizards of the Coast2016-09-20
  Official Ruling
  Gonti doesn't change when you can cast the exiled card. For example, if you exile a creature card without flash, you can cast it only during your main phase when the stack is empty.
• WWizards of the Coast2023-07-28
  Official Ruling
  The six types of mana are white, blue, black, red, green, and colorless. Snow mana is not a type of mana. Gonti, Lord of Luxury won't let you pay a snow cost using mana produced by a nonsnow source.

Rulings via Scryfall