anotherfandom asked: If Grusilda mashes up a creature I own and a creature an opponent owns, what happens if someone casts Brand or activates Homeward Parh? I am leaning towards splitting them up. Also, can she mash an augment with something other than a host?

If more than one player controls the same permanent, the game forces them to have a challenge to see who gets control of the creature. The challenge can be any kind of challenge you and your opponent can agree on. If you can’t agree, roll a die and the higher roll wins.