Advanced format ruling
Radiant Mirror Force
Card effect (current official text)When an opponent's monster declares an attack while they control 3 or more Attack Position monsters: Destroy all Attack Position monsters your opponent controls.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.