The diminished 7th scale is such an amazing scale to use in conjunction with standard minor and pentatonic scales. It creates a very mild dissonance and, if used well, can really add another dimension to your soloing.
I find that one of the biggest challenges in rock soloing is creating tonal tension while still retaining a sense of intensity. If I get too adventurous with my tonality, it gets too fusion/jazz-like, and I loose the intensity.
The diminished 7th scale creates enough dissonance to prick the ears of the listener, and the notes within the scale have a solid relationship with most of rock's typical scales, such as the pentatonic.
This lick is an example of how far you can take these ideas. It's less of a solo than a demonstration of ways to incorporate the techniques up and down the neck.
I start this lick with a 4-note-per-sting legato and tapping run, with the 4th note of every line being tapped. This is a little different from normal, as we're not picking the first note. Instead, we're relying on the index finger to hammer the first note on every string rather than it being in position and picked.
We repeat this lick by moving it up and down the scale, while, on the second time through, we move into the arpeggio section. This is my preferred way to play the arpeggios with tapping, I feel that it creates great flow and you can transition from position to position very easily.
From here we move into 3-note-per-sting legato lines, then finish with two arpeggios. Same shapes as before.
As you make your way through this lick you will notice that the actual patterns/shapes of the legato and arpeggios are always the same, this is the beauty of using the diminished 7th scale, the patterns always repeat. Some of the challenges are obviously the wide intervals and stretching, but like anything on guitar this is something that you can work on too!
Thanks and I hope you enjoy!