So there's a book out now about Swedish death metal that seems extremely rad. I've been reading about that on the internet today, so now readers of my internet get to read about it too.
All of this thinking about Swedish death metal got me thinking about Crematory, who put out one of the best demos from the scene. The thunderous mid-tempo parts, as well as the cymbal catches into downtuned tremolo-picked riffs are all present, but what defines this band's compositional style is the way that they work with phrases.
Each phrase might consist of a self-contained riff repeated four times or it might have an A/B ending structure or it might be more free-flowing (Wrath of the Unknown at ~2:25), which creates an interesting cyclic effect as the riff is repeated. When phrases of these differing varities are played over fast metal drumming, there is room for the rhythms created by the guitars to take on a life of their own independent of the typical rock back beat. The aforementioned riff in Wrath of the Unknown starts off as a cyclic little phrase, then is varied into a more conventional two-part phrase through a change in drumming accompanied with a substitution in the first part of the riff.
One of the hallmarks of good songwriting, metal or otherwise, is knowing how to work with these different types of phrases in order to create a relevant and engaging work. The ear is very good at picking out cadences, and as such they present one of the most effective tools for creating suspense or resolving as expected.