Valkyrian Guard

[REQUIREMENT]When your opponent Normal or Special Summons a monster. [EFFECT] Special Summon 1 Level 4 Spellcaster Type monster from your Graveyard to your field in face-up Attack Position. Then, you can change up to 3 Attack Position monsters on your field to face-up Defense Position, including "Magician's Valkyria". This turn, while the monsters changed to Defense Position by this effect are in face-up Defense Position, they cannot be destroyed by battle.