Ghost Roaster is pranking Blueblood because he was actually resting in the mirror until Blueblood woke him up. Ghost Roaster decided to prank the clueless stallion and took the form of Blueblood's reflection. The Skylander had fun pranking the stallion until the prince mentioned the other Skylanders in a rude way. Ghost Roaster didn't like that....not one bit. Blueblood is basically in for it now since Ghost Roaster returned to his normal form.