
Oozaru (Great Ape)
When any Saiyan with a tail is exposed to the light of a full moon, this sets off a chain reaction from a gland in their tails and causes them to transform into a giant ape (Oozaru is Japanese for "Big Monkey"). This causes the Saiyan's power to be multiplied by 10. With training, this form can be controlled but Goku and Gohan were never trained this way so they went out of control and destroyed all in their way.