Alrund's Epiphany

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.

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.

Exiling Alrund's Epiphany as it resolves is part of its effect. If Alrund's Epiphany doesn't resolve, it will be put into its owner's graveyard. If it's exiled this way, it's exiled face up and doesn't become foretold.