Castle Ackle is located on the planet Omiros and is the stronghold of the wizard Zalt. He-Man, Orko, and Battle Cat came to this place to find the Gronk, which had Orko's magic in him.
Outside the gate, their way was blocked by a Giant Guard, but after He-Man caused the giant to defeat himself, they had no trouble entering the castle. Inside, they faced various magic tricks from Zalt, but again He-Man managed to trick the magician into defeating himself, using the power of Grayskull and his sword of power.