Do We Have This One? Up for Grabs.
So you've got a big powerful villain that's been Orcus on His Throne, or in general setting up plans to take over the world. However, there's just one major problem. His evilness has been partially sealed in a can, preventing him from using his full power. The villain himself may have done this to further a Xanatos Gambit, but either way, for some reason the villain is not in possession of the MacGuffin
or his full powers.
Lord of the Rings has this with Sauron and One Ring.
Another example would be Muu from Monster Rancher. He's separated from his ancient ( and MUCH more powerful) body.
See also Zeref from Fairy Tail.