Another app in this series from Massive Stylus. Here’s the description of Drumstep:
Drumstep is a drumstep music center for the iPhone. Play ridiculously filthy wobbles wherever you are! This release comes with 3 drumstep packs. Each drumstep pack has 16 wobbles, 4 noises and 4 beats to play along with. This our 2nd and current favorite release in the Wobble Bass Suite following the prior releases; Wobble, Whomp & Glitch.
The app is priced at $0.99.