the awesome upward strike can be done after any 4 A or S attacks, not necessarily S-S-A-A. and I think the best combo is the D move after 3 A/S attacks. you can also use it to hit the grasshopper-like minibosses while staying out of their attack range
to hit vandheer in hard you when he's in his last phase you can also double jump above him when he uses his W attack (lighting) and hit him with your D move.