Compelled Duel
Adventures in the Forgotten Realms — Common
Sorcery
Compelled Duel rulings:
2021-07-23: Only one creature is required to block the affected creature. Other creatures may also block it and are free to block other creatures or not block at all.
2021-07-23: If each creature the defending player controls can't block for any reason (such as being tapped), then the affected creature isn't blocked. If there's a cost associated with blocking the affected creature, the defending player isn't forced to pay that cost, so it doesn't have to be blocked in that case either.