Tengu format ruling
Ring of Magnetism

Card effect (current official text)You can only equip this card to a monster on your side of the field. Decrease the ATK and DEF of a monster equipped with this card by 500 points. In addition, all the monsters on your opponent's side of the field can only attack the monster equipped with this card, if they attack.
Rulings
- If there is a monster equipped with Ring of Magnetism on the opponent’s side of the field, if your monsters are going to attack they must attack the equipped monster. Even Toon Monsters, Inaba White Rabbit, and monsters like Jinzo #7 and Queen’s Double that can normally Attack Directly must attack the equipped monster.
- If you have two or more monsters on your side of the field equipped with your Ring of Magnetism cards, you choose which monster will be attacked.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.