The Seal of Orichalcos

Field Spell Card

All monsters you control gain 500 ATK.

Once per turn, this card cannot be destroyed by card effects.

While you control 2 or more face-up attack position monster, your opponent cannot target your monster(s) with the lowest ATK for an attack.  When this card is activated: Destroy all Special Summoned monsters you control.  You cannot Special Summon Monsters from your Extra Deck.  You can only activate "The Seal of Orichalcos" once per Duel.