This one's an extra I decided to throw in, it's a trick commonly executed by the likes of Per Nilsson (Scar Symmetry) or some of the more bombastic, sometimes over-the-top players like Bumblefoot.
The concept: Creating wacky-sounding dissonance through harmonizing with the minor 2nd interval.
First, let's analyze the minor scale so we can see exactly where these notes come into play. For our purposes, let's practice in E minor.
Check out the first part of the tablature below entitled "Concept (Part I)". What we see is a straight-forward E minor scale with the intervals highlighted that land one semitone (one fret) apart. In minor scale formula: (2 to b3... or 5 to b6). We'll simply re-arrange these notes in a higher scale format so that we can allow the notes to ring together and produce the effect. This lick will work in almost any minor scale context, and if done "tastefully", can really catch listeners off guard in an exciting way!
"Concept (Part II)" shows us the exact sets of notes (F#/G... C/B), one octave higher and in a fingering possible for harmonization.
Both Exercises A & B contain minor 2nd harmonization, A, in E minor, and B, in B minor.
Be creative with this tool; try re-arranging some of the notes in your favorite scales and try it out. This type of note choice is relatively ignored due to it's heavily "unpleasant", "resonating" sound, but it's a great way to break free of "nice"-sounding, always-fitting harmony.
Mature phrasing is what sets apart the boys/girls from the men/woman, so never over-look it. The emotional conviction attached to your sound may mean the difference between an audience captivated in tears, or walking away emotionally unaffected. Let the guitar say what you can't.
That's it for this month, have fun, and I hope you've taken away at least a few new tricks to add to the trick bag!