Advanced format ruling
Ultimate Obedient Fiend
Card effect (current official text)This card can only attack if this card is the only card on your side of the field and if you also have no cards in your hand. The effects of Effect Monsters that this card destroys are negated.
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.