Corrosive Scales

Target 1 Insect monster you control; equip this card to it. While you control the equipped monster, your opponent's monsters cannot attack Insect monsters, except the equipped monster. While this card is equipped to a monster, each time your opponent Normal or Special Summons a monster(s), OR activates a card or effect, place 1 Scale Counter on each face-up monster they control. Each monster your opponent controls loses 100 ATK/DEF for each Scale Counter it has.