He-Man and the Masters of the Universe

Adam, Teela and Cringer are exploring the Valley of Power, which contains magical water which imbues anyone who drinks it with great power. But a stranger called Danavas is also in the area, and has stolen the egg of a Mother Rogue. When the baby bird hatches, he makes it drink the water and gain its power, so he can control it for himself. The bird grows to giant size, and soon the Royal Palace is in danger from Danavas' adopted pet!