Ben 10 Underworld !
When 10 year old Ben, his cousin Gwen, and their grandfather Max are on their summer camping trip, Ben finds an alien pod on the ground. When he examines it, he finds a mysterious, watch-like device called the Omnitrix. The device attaches itself permanently to his wrist and gives him the ability to transform into a variety of alien life-forms, each with its own unique powers. Along with Gwen and Grandpa Max, Ben embarks on a summer long adventure to fight evil, both extraterrestrial and earthly.