He-Man and the Masters of the Universe (1983)

S1E12 Disappearing Act

After He-Man thwarts their latest scheme, Skeletor and Beast Man devise a plan to eliminate him for good. Using invisible helmets, they infiltrate the Royal Palace and abduct Prince Adam, intending to use him as bait to draw out He-Man. Unfortunately, a mishap with one of Orko's spells sends the Sword of Power back to Eternia’s ancient past, preventing Adam from transforming into He-Man. While the Sorceress sends Orko and Cringer on a mission to recover the sword, she assigns Man-At-Arms the task of deceiving Skeletor into thinking He-Man is nearby when he is not.