The first time I heard the Pantera song "Shattered" (from 1990's Cowboys From Hell), I couldn't believe how nasty the whole thing sounded. To me, it was the perfect metal tune. Killer riffing...rippin' leads...screaming vocals...a hell of a Grand Finale...and it got its point across in a little over 3 minutes; it became my all time favorite Pantera song. In fact, I don't know why they never played it in concert any of the seven times I've seen them. I think it is a totally underrated CFH song.
It's kind of like adding some guts to the end of the riff to make it sound a lot HEAVIER. I'm sure there are a lot of bands out there that do this sort of stuff, but "Shattered" was the one that really opened up my eyes and ears.
So eventually, I got a few ideas from this one song to come up with my own stuff. This is probably one of the best examples I came up with so far.
Playing measure one over and over again would get a little boring. So by using the ideas that I got from "Shattered" the riff sounds like there is a lot going on even though I'm playing the same notes again and again. Every single note played in the first measure is played with power chords in the second measure. For the D (4th note in the first measure), I substituted an open chord (open D and open G string). My hands are not that fast to nail a D5 yet. As for the power chords, I simply slide them back and forth to make it sound as fast as the single note sequence; otherwise it would sound too "choppy and sloppy." This way, the whole thing sounds smoother.
Hopefully this will give you some ideas to come up with your own kind of Call and Response type riff. I suggest listening to other Pantera riffage to get you inspired when you can't come up with anything. Until then, see ya next time.