If the turn player Summons exactly 1 monster: Destroy it, and if you do, the controller of that monster Special Summons 1 "Mask Token" (Spellcaster/DARK/Level 1/ATK ?/DEF ?) to their field, which cannot attack directly, with ATK/DEF equal to what the destroyed monster had on the field. You can only use this effect of "Ecole de Zone" once per turn. If this face-up card leaves the field, destroy all "Mask Tokens" on the field.