I found that in Single Player my Vanguard character can do a downward smash attack with the Melee button, similar to Nova. It activates when I Run and then Melee while running (X+O on PS3) like I'm doing a regular Strong Melee.
Shepard hits the ground for a small shockwave. It's got a bit of an AOE so it's not the same as the normal punch. It's not Nova since it doesn't drain my Biotic Barrier, and it doesn't initiate a cooldown; it's a Melee skill best I can tell.
I tried doing this move in multiplayer but it doesn't work. No matter what I try, my character does the Strong Melee normally, not the downward smash. I even tried using a Vanguard character and nothing.
Is there anything I need to do to unlock/use this attack? Why doesn't it work in Multiplayer?
I know the Asari Adept has a similar "shockwave" attack, but that's just the Asari's normal heavy melee. This is a different attack I have in addition to the normal heavy melee.