It seems no one has noticed that if you press A+K at the exact time your opponent does an attack it repels(cancels out) the attack. This also seems to affect any Mid moves (eg: Horizontals, Verticals and Kicks).
Someone has noticed - I'm pretty sure I've mentioned elsewhere you can CH and even clash (?!) a throw with A+K. Try it on your friendly neighborhood Astaroth.
If you have time to prep while someone is in air (Poe example of 8B+K) you can also 8B+K A+B for a better option.
You can A+K directly from 3B if you tap forward - but you don't get a soul charge for it, so it's not the best...
Some of my notes:
Anything that puts a character face-to-face in collision (that is, walking forward against another characters face) may not cause the offensive hitbox to connect. Anything that's somewhat offset is nearly guaranteed every time. A+K does a very tiny TS so this isn't really that difficult to get set up.
Characters charging forward (Poe/Pie 236, Pie 66B, Nightmare 236, Xiba's 66BBB, etc) will usually always get hit by the CH even though the attacks are certainly not mid/high horizontals (this includes throws) as long as you beat their impact frame (obviously).
Super armor overrides clash, so trying to A+K Astaroth's Bullrush BE will get you run over if the GI doesn't catch (no CH, no clash).
Moves in TC or FC still get hit by the counterhit during standing frames with timing.
Mitsurugi's MST and backstep causes all sorts of weird problems with a lot of Yoshimitsu's moves including A+K.
I don't have good luck hitting Viola or Pyrrha's unblockables as it seems I collide with the character further away than the offensive hitbox goes. It makes no sense. Same issue with 1K/MED K and iMCF. It's not really consistent, but it's not the best option, anyway.