It's two layers essentially:
The first is a basic punchy sub rolling bass, I'm sure there are hundreds of tutorials on it so I won't get into it.
The other layer is that grit you mentioned. It's essentially a saw wave with an open filter & very high resonance, decay around 450ms and everything else 0 on the amp env, and then very heavy (very very heavy) bitcrushing added. The bitcrushing will essentially over-power most of the original synth, so things like oscillator choice will have limited effect.
The main thing to focus on when making that second layer is to create an open, 'talking' style basic synth that sounds like your generic dubstep talking basses, then bitcrush the hell out of it.
Add the two together and WAMBO!, you've got your synth.
