“Because I'm an evil Koopa Wizard! I don't need a reason to be mean and nasty. It's my nature!”
Mario, Luigi, Princess Toadstool, and Yoshi first encounter Wizenheimer while searching the Enchanted Forest for Oogtar the Caveboy, who is missing. After Luigi bumps into him in the forest, the Koopa Wizard takes Mario, Luigi, and Toadstool prisoner and forces them into a nearby Warp Tube, threatening to blow the trio up with a Bob-omb if they don't obey. The Warp Tube leads to Wizenheimer's Haunted House, where he shackles his prisoners in the basement.
Wizenheimer later captures Oogtar by simply warping him into the dungeon after the caveboy arrives at his door and demands the princess and Mario brothers. Wizenheimer is later found in the basement when Yoshi ventures through the house to save everyone. The Koopa Wizard tries to attack Yoshi, but Yoshi, under suggestion from Oogtar, eats his wand, spitting out a magic blast that frees his prisoners. Mario then jumps on Wizenheimer's head, sending him falling down the staircase.
A running gag in the episode involves Wizenheimer's name continuously being mispronounced by the other characters. Such names include: Wisenheimer, Wiseacre, Wizenmeanie, Wisecracker, Wizen-wise guy, Wisen-whatever, and Wisen-whatchamacallit.
Names in other languages