Did some lab work to try and figure out more Hisako dirt (nasty counterhit setups) and came across something really weird. Hisako can combo off her jab on counterhit, but I noticed that for some reason that confirm does quite a bit more damage than doing the same counterhit setup with st.MK as a starter. The result was weird enough that I decided to test with more buttons.
The combo paths and resultant damages are:
LP->MP, HP, HP ORZ->heavy AD->dmg ender (30%)
MK->MP, HP, HP ORZ->heavy AD->dmg ender (26%)
cr.MK->MP, HP, HP ORZ->heavy AD->dmg ender (26%)
st.HK->MP, HP, HP ORZ->heavy AD->dmg ender (29%)
And trying with heavier punches yields the same. Tested to see if it was somehow wrath dependent, but as to be expected that’s not the case. It’s super weird - the heavy buttons hit significantly harder than the light for purposes of the 200% first-hit bonus, so couldn’t really think of a compelling reason why the light confirm combo should hit so hard. Messed around a bit more and discovered that the first rekka hit seems to matter a lot, perhaps for building PD?
Using heavy rekka opener:
LP->HP, HP, HP ORZ - not possible to link LP->heavy ORZ, even on counterhit
MK->HP, HP, HP ORZ->heavy AD->dmg ender (33%)
cr.MK->HP, HP, HP ORZ->heavy AD->dmg ender (33%)
st.HK->HP, HP, HP ORZ->heavy AD->dmg ender (36%)
These results led me to wonder if there was anything special about the rekka first hit, so decided to test that too.
Different Strength Rekka Damage Values:
LP, HP, HP ORZ->heavy AD->dmg ender (24%)
MP, HP, HP ORZ->heavy AD->dmg ender (25%)
HP, HP, HP ORZ->heavy AD->dmg ender (26%)
So it seems like the rekka first hit doesn’t really matter very much except for the purposes of scaling more heavily with the normal that comes before them. They significantly upgrade the damage on normal->combo, but raw don’t make much of a difference at all. Which leads me back to the question of why the LP confirm hits harder than either button if you confirm with an MP rekka first hit. This made me curious about if the MP rekka first hit was bugged somehow, so did one last test.
Light Rekka Confirm Damage Values:
LP->LP, HP, HP ORZ->heavy AD->dmg ender (23%)
MK->LP, HP, HP ORZ->heavy AD->dmg ender (25%)
cr.MK->LP, HP, HP ORZ->heavy AD->dmg ender (25%)
st.HK->LP, HP, HP ORZ->heavy AD->dmg ender (28%)
Here the combo damage behaves like you would expect it to, with heavier button confirms dealing more damage than lighter ones. So I’m guessing that MP ORZ first hit is just weirdly bugged? Any thoughts @Infilament?
Apologies for the somewhat rambling nature of the post - was writing it out as I was testing. Anyways, I thought this was a neat little find. Not sure how useful it will be since light confirms require counterhits and it’s not really possible to guarantee those, but might be cool on some hard read type setups. 
