The "slag" became the size of a single head not because the quantity decreased, but because I compressed it into this volume.
Usually, the "slag" and my flames are combined, and only when I need it (though I've never actually needed it before) does it separate from the flames. My flames can be compressed into a single point, and the "slag" within them can also be compressed along with the flames.
In fact, even without the flames, I can compress it to this size. Although my superpower is ultimately about manipulating fire, not "slag," I recently discovered another property of the "slag."
