Pyroclastic flow is Ice Cube's gangsta flow. It's his ability to rhyme to cool beats, and gangsta lyrics.
Official definition of Pyroclastic flow by Ice Cube :
What's the definition of a pyroclastic flow?
That's what happens when a volcano blow
That's what happens when Ice Cube starts to flow
Red hot lava mixed with saliva
Pulverising everything in its wake
Nothing can survive a pyroclastic flow