One of my teammates was preparing for a competition last week (he double medaled!) and he mentioned that he wanted to learn more combination attacks. He has been working on his closed guard recently, which is my favorite position.
Depending on how you choose to play the closed guard your partner may feel completely trapped or under constant attack (or ideally both). Currently, I focus on keeping my partner trapped when I using my guard because it is a position I feel safe in with a larger partner. But I would like to incorporate more combinations so my guard can feel both vicious and suffocating.