Mastiff Phalone is wild, and its behavior cannot be modified to accept the presence of humanoids. It cannot be trained to abandon its wild instincts and will generally continue to do whatever it wants. As creature handling goes up, a character can better predict what this creature will do and empathize and understand it despite being unable to tame it. With proficiency (+3) a member could manage to successfully own and cage this creature but not safely interact with it and influence its behavior, with a better understanding and ability to manage this Mastiff Phalone coming with mastery (+5).