Prison guard; Butterfly+Full Guard+Rubber Guard. If you have a solid grasp on those first 3 guards, you will benefit the most from Prison Guard IMO as it is a hybrid guard that includes elements from each of those. The first "trip wire" in the prison guard is the basic buttefly sweep using ur one butterfly to elevate to the opposite direction and using ur homie control to take out the base or direct the upper body as needed. Once that's tested, the most popular and IMO lucrative path, is straight to the back using your deep underhook from homie control to slide over(Koala Bear style, shout out to Melbourne, lol) and turn your homie control into over-unders on their back without ever breaking your grip. Your leg is already on the back, under-hook side, so you just slide your hooks in and voila, let the RNC parade begin! If both of those options get shut down, you can isolate the arm you have trapped into either; an arm-triangle off your back(gotta have SQUEEZE), an EZ New York(Rubber Guard), OR you can transfer it all over to a swim move if your a fucking ninja

That's my take on it, I love it, use it all the time, you have to change it up at HQ where everyone knows the same shit and how to neutralize and reset you and...zzzzzz, aim for the head, go for the throat...