Advanced format ruling
Big Shield Gardna
Card effect (current official text)When a Spell Card is activated that targets this face-down card (and no other cards) (Quick Effect): Change this card to face-up Defense Position, and if you do, negate the activation. If this card is attacked, change it to Attack Position at the end of the Damage Step.
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.