When the active player uses a charm to move an opponent's unit to a battlefield they control, causing a showdown, who is the attacker and defender?

Ruling: The active player who used the charm becomes the defender. The opposing player whose unit was moved becomes the attacker.

Nuances:

• The key factor is which unit contested the battlefield, not which ability caused the movement
• The unit that was moved is the one that contested the battlefield, making its controller the attacker