"Wizards of Apartment 13B" is the one-hundredth episode overall and the twenty-first episode of the fourth season in Wizards of Waverly Place.
Alex and Harper receive a flyer for a hotel. They meet the hotel's owner, Dexter, who sells them Apartment 13B, which belongs to a floor for non-humans. They rent it, but Harper is forced to use a training wand that can only open things. Later at their apartment, they realize Mason lives on the floor. Mason will stop at nothing to win Alex back; Alex tells him she does not want a boyfriend, but Mason is relentless. That night, Alex and Harper throw a party, where the whole floor comes, including Felix. Mason goes to the party and uses Harper's wand to open Alex's heart. However, she flirts with an ugly giant. Mason tries again, but makes Alex opens her heart to Felix. Meanwhile, Theresa and Jerry trick Justin into going to Alex's apartment to drive him out of the house. When Justin arrives, he fixes Mason's mistakes by resetting Harper's wand and it is revealed that despite his actions, he misses Alex. Alex, freed from Mason's spell, is angry at Mason, and Mason, deflated, leaves. Outside their door, Dexter turns into Gorog when no one is looking. He wants revenge. Max appears in the apartment, and when Harper and Alex kick him out, he encounters Gorog, who gives him a flyer for a free camp. Max accepts.