Kimura lock is a powerful technique. It was introduced and named after one of the greatest judokas, Masahiko Kimura
I have been having a lot of success with it play bottom half-guard. While controlling the opponents arm with my bottom hand, I can edge it away enough to loop my other arm over.
The result is a powerful 2 on 1 hold. In the event of failure, I can easily reset to basic defensive guard of my preference.
Here is a good instructional video of the technique