2 Part Technique - Set up the Inverted Armbar by forcing the opponent to post out against the Hook Lift Sweep with Collar and Elbow Control from Butterfly. Since you have control over his elbow, he has no choice but to put his other hand to the mat for you to trap against your neck once it touches the mat. Chop down on his elbow joint with a a muay thai clinch-esque style control while you extend your hooks to sit up and crunch downward into an open space. If he begins to rotate his elbow toward the mat to relieve the pressure, use your forearms to steer his extended arm back to where you can apply pressure down again with your grip, not your own elbow.