Ultimate Spider-Man Season 4 Episode 20 - Strange Little Halloween Episode Title:Strange Little Halloween.Episode Description:On Halloween night, Spider-Man tries to go trick-or-treating when a strange magic engulfs Manhattan and has the trick-or-treaters becoming what they are dressed as. Spider-Man visits Doctor Strange, who claims that the responsible spell is on a quantum level. Spider-Man and Doctor Strange end up needing the help of Ant-Man in order to go to the Quantum Realm to find the source of the spell. Once there, Spider-Man, Doctor Strange, and Ant-Man find a reassembly Baron Mordo who attacks them with a construct that assumes the form of Dormammu, Ultron, and Doctor Octopus' nanite-enhanced form, which is only the beginning of its plot.