Corner combo starting with mb batarang...
MB batarang, f3, j2, 123, b23 = 34% (36% if you add a slide at the end).
This one is gonna take a lot of practice. Props to Reo for landing it in the final match of Civil War.
I think it might be possible to combo mb batarang into b3 midscreen but I haven't gotten it yet.
I've found a combo for it but it doesn't seem worth it, looks nice though. lol
Without Bats j.2 , 223 , B.3 , UP batarang MB, j.3, b.23 = 38%
With Batse j.2 , 223 , B.3 , UP batarang MB, j.3, b.23 rb grapple = 42%
With Bats and Two bars j.2 , 223 , B.3 , UP batarang MB, j.3 b.23 rb grapple MB j.3, b.23 = 46%
Edit: Found something a bit more damaging
j.2, 223, b.3, j.2, up batarang ex , j.3, b.23 = 42%