Thomas Rozdzynski's sideways reversal from sit-up guard: when they posture back, grab the belt, pivot behind and pinch the knees to sit them down. Less inverting than a classic roll-under.
Lachlan Giles on the arm drag from seated guard: win the wrist, drag to the armpit and immediately glue your chest to the trapped arm so they cannot pull it back before you come up to the back.
Wrestling up from seated guard to a single leg with three finishes: get behind and shelf the leg, intercept the step like a low single, or go between the legs when they sit their weight back.