Nightmare Magician (MP24-EN093) [25th Anniversary Tin: Dueling Mirrors]

If this card battles a monster, neither can be destroyed by that battle. At the end of the Damage Step, if this card battled an opponent's monster: You can take control of that opponent's monster. Once per turn, at the start of the Damage Step, if another monster attacks: You can destroy 1 card on the field.