The animation is good, quite good, I like the living room set, the voice acting was good
but the punchline is easily predictable and simple.
Also, I wasn't sure what tone you were going for. The opening shot's lighting and bright walls didn't give a sense of utter doom, and the music throughout didn't help. The ending shows why you picked it, but something darker upfront would have helped sell the big reveal by getting people into the mindset that you wanted them in.
I don't recommend using the exposed studs on the one wall, it gives a bad sense of unfinishedness, and would have looked a lot better covered in tiles or something. Now if all the walls in that room were built that way it would have been fine, but when just one wall is like that...Not so much.
To make it less predicable, I would have had one of two things:
Spoiler (highlight to read)#1, The traveler gives it to the guy on purpose, and is revealed to be a traitor.
#2, The kid kills Magnus, but gets addicted to the power and becomes even worse.
Still, you did a great job for a nine hour film.
I just wish you had used all your time and made something a bit more ambitious.