This app will allow you to set a delayed shutdown on your rooted device.
You can set how many minutes, and or how many hours until your device shuts down, and you can only stop it by pressing the cancel button in the app -- exiting or killing the app will not stop the timer.
Make sure you allow persistent root access, or instead of shutting down you will get a prompt from SU asking for access.
Email me about bugs or issues rating please! Remember not to 1 star me if your device isn't rooted!