Spell Proof Armor

Activate this Skill during your Main Phase and apply the following: • Machine Normal Monsters you control are unaffected by your opponent's Spell Cards or effects. • While you control no monsters, you can Normal Summon Machine Normal Monsters with 1 less Tribute. • If you have a non-Machine monster on your field or GY, flip this card over. This Skill can only be used once per Duel.