Phantasm Spiral Crash

Equip only to a Normal Monster. If the equipped monster attacks a Defense Position monster, inflict piercing battle damage to your opponent. When the equipped monster inflicts battle damage to your opponent: You can Special Summon 1 "Phantasm Spiral Dragon" from your hand, Deck, or Graveyard, and equip it with this card, then you can change 1 Attack Position monster your opponent controls to Defense Position. You can only use this effect of "Phantasm Spiral Crash" once per turn.