Imperious Mindbreaker is a rare Creature — Human Wizard card from Magic Online Promos (PRM), collector number 95305.
Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.) As long as Imperious Mindbreaker is paired with another creature, each of those creatures has "Whenever this creature attacks, each opponent mills cards equal to its toughness."