Equip only to a Level 5 or higher Fiend or Zombie monster.
When an attack is declared involving the equipped monster and an opponent's monster: You can make that opponent's monster lose ATK equal to the equipped monster's.
You can activate 1 of these effects;
● Fusion Summon 1 Fusion Monster from your Extra Deck, using monsters from your hand or field as material.
● Special Summon 1 "Doppelganger Token" (Level 5/ATK ?/DEF 0) with the same Type, Attribute, and ATK as the equipped monster.
You can only use this effect of "Spirit Illusion" once per turn.