Some of the tritone stuff works as well, but don't ask me I'm not a theory expert. Hence half the threads in this music theory forum are mine :P. Hope I helped some. I don't know about melodic minor for death metal, just doesn't seem to give the same feel, but maybe I just use it wrong. Also, don't forget your chord inversions and such.

[EDIT] Also, I forgot to mention, use diminished arpeggios to add a nice lead elemen to your uber brutality.

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