Démone Subterreur MACR-FR082

During each player's turn, when your opponent activates a card or effect: you can send this card from your hand or field to the Graveyard, then target 1 "Subterror" monster you control. Negate the activation, and then change the targeted monster to face-down Defense Position. You can target 1 face-up monster you control, change it to face-down Defense Position, and if you do, Special Summon 1 "Subterror" monster from your hand or Graveyard in face-up or face-down Defense Position. You can only use each effect of "Subterror Behemoth" once per turn.