I realize that my question is inherently subjective to some degree but I think there might still be some prescriptive techniques to be gleaned from it from experienced composers.
I know that uncertain timing, sudden dynamic bursts, and glissandos can be very effective, but I'd like to exclude dynamics, syncopation, and rhythms from the discussion and limit discussion specifically to harmonic or tonal aspects.
For starters, let us just consider two chords. Some obvious tactics occur to me:
- Jump every note a tritone up or down. Although this may sound especially evil if one or both chords are major, it certainly has a disruptive feel to it.
- Make both chords minor -- although e.g. moving from Am to Em (both chords in the key of C) doesn't sound especially evil. I want to say that intervals of a fourth or fifth do not quality as "evil."
- The two chords have few (or zero) notes in common.
- dissonance required?
Is there any canon or definitive list of tricks that's been spelled out anywhere? Or perhaps we could start with some ancient list of what not to do and find ways to violate the rules? Or minimally some brief list of "most evil chord pairs."
Any input would be much appreciated.