REDU format ruling
Defense Draw

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)During your opponent's turn, at damage calculation: Make the battle damage you take from this battle 0, and if you do, draw 1 card.
Rulings
- You cannot activate Defense Draw if you will not receive Battle Damage from the attack.
- You cannot activate Defense Draw if there are no cards left in your Deck.
- You cannot activate Defense Draw while your opponent controls a face-up Protector of the Sanctuary.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.