Xiaolin Showdown - Season 2 Episode 8 The Sands of Time
Overview: After receiving a warning message from Omi in the future, the Warriors set out to find the time-traveling Shen-Gong-Wu, Sands of Time. In the message, future Omi explains that evil is ruling the universe, and the Sands of Time is the key to changing the future. Jack, however, beats them to it and uses it to travel back in time to recruit some of the world's ruthless villains. He also brings his future self into the present time, knowing that future Jack already knows the locations of all the Shen-Gong-Wu before they reveal themselves!