The minor 7b5 chord is mostly used in Jazz, but the sound of those notes fits the metal style quite well.
The scales you can play over that jamtrack are:
- G m7b5 pentatonic
- the G locrian mode (Mode VII of Ab major)
- the G aeolian b5 mode (Mode VI of Bb melodic minor)
- G Dorian b5 Scale (Mode II of F harmonic minor)
Have fun and leave me a comment – especially if you want to share a soundcloud file or youtube video where you use it!