In the episode "Dawn of Dragoon", He-Man had to travel to Trolla, but when he entered the portal to Trolla, him and Battle-Cat had reverted back to Adam and Cringer and were powerless against the Dragoon until Cringer (accidentally) figured out that everything was backwards in Trolla. With that in mind, Adam said "Grayskull of power the By!!!" ...and changed into He-Man!