[2S > jc > j.B > j.S]xN
This sequence works easily when the opponent is in the air. It's a great fallback for stray hits.
The key to linking multiple loops during a combo is inputting 2S and j.B as soon as possible, which is made easier thanks to the game's input buffer.
If maximizing for damage, you can skip j.B, but the timing is generally not easy. The loop itself is harder to execute when starting from a raw 2S as opposed to mid combo, so you should practice it in a BnB instead.
If you're not feeling confident about looping this variation, you can input 2BGuardLowStartup10Recovery26Advantage-11~-20 or 5B
GuardAllStartup9Recovery19Advantage-3 after landing and then cancel into 2S instead for generally easier combos, though this will result in less damage. Experiment and find what works best for you.
Doubles as an effective way to go into enders.