Struggle for Skemfar

• WOTC Official Reminder Textofficial rules
  Fight — Each of those creatures deals damage equal to its power to the other.
• WOTC Official Reminder Textofficial rules
  Foretell — Foretell [cost] (During your turn, you may pay and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

• WWizards of the Coast2021-02-05
  Official Ruling
  Casting a foretold card from exile follows the timing rules for that card. If you foretell an instant card, you can cast it as soon as the next player’s turn. In most cases, if you foretell a card that isn’t an instant (or doesn’t have flash), you’ll have to wait until your next turn to cast it.
• WWizards of the Coast2021-02-05
  Official Ruling
  Because exiling a card with foretell from your hand is a special action, you can do so any time you have priority during your turn, including in response to spells and abilities. Once you announce you’re taking the action, no other player can respond by trying to remove the card from your hand.
• WWizards of the Coast2021-02-05
  Official Ruling
  If you choose two target creatures and either target is an illegal target as Struggle for Skemfar tries to resolve, neither creature will deal or be dealt damage.
• WWizards of the Coast2021-02-05
  Official Ruling
  If the creature you control is an illegal target as Struggle for Skemfar tries to resolve, you won’t put a +1/+1 counter on it. If that creature is a legal target but the other creature isn’t, you’ll still put the +1/+1 counter on the creature you control.
• WWizards of the Coast2021-02-05
  Official Ruling
  If you’re casting a foretold card from exile for its foretell cost, you can’t choose to cast it for any other alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, those must be paid to cast the spell.
• WWizards of the Coast2021-02-05
  Official Ruling
  You can cast Struggle for Skemfar targeting only a creature you control.

Rulings via Scryfall