Illusory Gains strikes me as a rather strange card with the potential for some rather unique interactions, one of which I'm hoping someone might be able to explain to me. Take this situation: My opponent has a Bear Cub and an Baulduvian Bear, I cast Illusory Gains on the Bear Cub and the cub comes under my control. I end my turn. On my Opponents turn he attacks with the Baulduvian Bear. I declare the Bear Cub as a blocker. After blockers have been declared but before damage my opponent flashes in a Ashcoat Bear, so I must attach Illusory Gains to it and lose control of the Bear cub. What happens?
Is the cub removed from combat and nothing takes damage? The only thing that is changed is who controls the creature, so it is still the same card (unlike if it had been exiled and returned).
Do both Bear Cub and Baulduvian Bear take 2 damage from each other?
Or does something else happen?