After retiring from professional voice-work, Erwin has not done official publicity appearances due to his shy nature.
He often unveiled new weapons or devices to help He-Man.
Castle Grayskull was the source of He-Man's powers, where the Sorceress lived, who granted Adam his transformative abilities and communicated with him.
Which leads us to our next point.
This series retold the Masters of the Universe story from the beginning.
See this on Greek legends to learn more.