If the card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
Sinister Concierge
If the spell requires any targets, those targets are chosen when the spell is finally cast, not when it's exiled.
You can exile a card in your hand using suspend any time you could cast that card. Consider its card type, any effects that modify when you could cast it (such as flash) and any other effects that stop you from casting it (such as from Meddling Mage's ability) to determine if and when you can do this. Whether you could actually complete all steps in casting the card is irrelevant. For example, you can exile a card with suspend that has no mana cost or that requires a target even if no legal targets are available at that time.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Tomas Duchek
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
