If you run forward for about one second you start building meter.

Slade

[14] Master
lol wut

That's really weird. The devs seem to really hate spacing this time around.
 

Harry

[10] Knight
I guess it's a way to reward you for you being brave/dumb enough to run at your opponent for a second+. The initial amount of meter is about a sixth of half a bar, then it just steadily goes up. I think it would've been better to just give people meter for dashing forward the that, but it's weird they even did it in the first place.