Lava Release: Rainbow Obsidian Flow

After conjuring lava from the ground, the user cools it at a specific pace, producing rainbow obsidian. The user is able to control the obsidian by remotely by manipulating the magnetite nanoparticles with the obsidian. The particles themselves are what produce the iridescent, rainbow-like sheen, hence the techniques name. The user can also change the frequency of the chakra to keep magnetically skilled shinobi from controlling the obsidian shard sand, and can return it back to lava and/or chakra for reuse.