SMG4: Mario's Mask Of Madness is the forty-sixth episode of Season 10 and the five hundred and ninety-eighth overall to be uploaded by SMG4.
This episode was aired on November 28, 2020.
Mario finds a weird mask that makes everyone go a little coo-coo crazy...
As Mario was walking out of the castle, singing You're Mine by DAGames, he met the Happy Mask Salesman, who sets up shop outside of the castle. As the salesman tried to offer his masks to fight against the current pandemic, Mario instead salvages his bag of forbidden masks, including Majora's Mask which ran away, forcing the salesman to chase it. Then, Mario found a mask in his likenesses, and puts it on for himself, but finds it useless. Dropping it on the ground, Luigi found it, and wore it, and was cursed by the mask as it controlled his body.
By then, the controlled Luigi began to act just like Mario, with Mario approving it while it caught the attention of Meggy and Axol. As Meggy tried to greet the cursed Luigi, he ran away, causing the rest to apprehend him, while Mario took away the mask by ground pounding on him. The ejected mask then became sentient, later controlling Axol.
As the cursed Axol went out of control, the rest tried to stop him, but failed as Axol threw curse-masks at them, turning them into cursed versions of themselves. A particular mask eventually anthropomorphised Melony, who became a beautiful yet silent and sleepy anime girl. As Melony walked to a bush to sleep, the cursed Axol walked up to her and scared her, causing him to be slapped and the mask removed. The now uncursed Axol removes the masks from his friends, and they all immediately walked to the sleeping Melony. Eventually, the Mario Mask later cursed Meggy, who became too powerful for the rest to defeat.
Fortunately, Mario had a plan. He woke and made Melony to use her hacking skills to call for an Uber Eats delivery of a plate of spaghetti, in which he placed the Beeg SMG4 mask to enlarge it to distract the cursed Meggy. Eventually, the three apprehended her and removed the Mario Mask. As the Mario Mask was about to curse them again, it was later subdued by the salesman. As the salesman cleaned up everything, everyone was relieved until the salesman tried to remove the mask from Melony, but failed, causing confusion among the brothers and Meggy, while Axol was infatuated.