These are the first four armdrags you should learn for BJJ and submission grappling. Once you learn them on your feet it’s easy to apply the same techniques on the ground from the butterfly guard and many other positions.

If you’re interested in making the armdrag one of your main attacks I can’t recommend The Armdrag and 2 on 1 Formula instructional enough. It features ADCC Open and No Gi Worlds black belt gold medalist Rob Biernacki, who is an armdrag genius. More info here: https://www.grapplearts.com/the-arm-drag-and-2-on-1-formula/

This is one of the coolest ways to take the back from the butterfly guard https://www.grapplearts.com/armdrag