If the target creature is an illegal target as Riverwheel Sweep tries to resolve, it won’t resolve and none of its effects will happen. You won’t exile any cards.
2025-04-04
You pay all costs and follow all timing rules for cards played this way. For example, if the chosen exiled card is a land card, you may play it only during your main phase while the stack is empty.
Tap target creature. Put three stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.
