The monster riff from Black Stone Cherry's 2011 single, White Trash Millionaire is in drop B tuning (low to high: B F# B E G# C#) and combines single-note riffing with powerchords.
You need to be careful when playing in this tuning, especially if you haven't changed your strings to a thicker gauge. Don't press too hard, particularly when getting stuck into the riff, or you'll push the notes out of tune.
The riff itself is fairly straightforward and shouldn't pose too many problems, but the second half does feature a bend on a powerchord.
Hold the chord with your third finger and place your first and second fingers behind it to add strength and control. Bend the strings towards the floor and release them in a quick motion. Maintain pressure into the fretboard to stop the notes from choking out.
Get the sound
You're looking for a modern, high-gain distortion to give the riff the power it requires. Boost the bass and treble and cut the mids to get the traditional 'scooped' metal tone. If your amp doesn't have enough gain, then add a distortion pedal into the mix.