The crucifix is a really underutilized way of controlling someone’s back. Instead of using your legs around the waist as hooks, you rotate and use your legs to control and isolate an arm.
This makes their arm vulnerable for submissions AND they can’t defend chokes as easily, making this position a real threat to anyone you put there. Thomas Lisboa is one of the best from here, having racked up a ton of victories by relying on it as a submission trap. See how he has been able to take a simple position and turn it into a reliable and razor-sharp submission chain as he walks you through his whole gameplan around getting the tap from the back.
Once you really understand how powerful the crucifix is, you will keep finding new and exciting ways to flow to it from your regular game. Once he has shown you the chokes and joint locks that he has had so much success with, Lisboa goes in depth into how he secures himself in the crucifix with tons of entries that you can start using today.
Anytime you see the back, you can apply a crucifix, and it flows so perfectly with kimura traps and guard passes that you can start adding it into your regular everyday sparring as soon as possible.