A simple rotation of the sandbag (or kettlebell, if no sandbag is available) while descending into a reverse lunge will challenge your strength and core stability in the transverse plane.
When you add in the power of a swing, what you wind up with is a really cool explosive movement – the swing requires decelerating the implement at the bottom of the movement before you explode from the lead leg into hip and knee extension.
A beastly set of traps is a sign of a serious lifter, but too much shrugging can cause postural problems down the line. Is there a perfect trap exercise that builds a serious yoke, without the drawbacks? Check this out.