Omnispell Adept

• WWizards of the Coast2018-10-05
  Official Ruling
  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.
• WWizards of the Coast2018-10-05
  Official Ruling
  If you cast a spell “without paying its mana cost,” you can’t choose to cast it for any alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, such as that of Severed Strands, those must be paid to cast the card.
• WWizards of the Coast2018-10-05
  Official Ruling
  You may cast a sorcery this way even if it’s not your turn.

Rulings via Scryfall