Kohitar the Xenolith
Kohitar (Mountain of Darkness) the Xenolith is one of the three lieutenants of Dr. Petra Pufferfish. They are a RADIOACTIVE GEM TALOS covered in an OBSIDIAN LAVA TALOS via a symbiotic relationship.
Their gem core is the Koh-i-Noor, the largest diamond in the world, it was in the Crown of the regent of the UK.
It is able to build incredibly energy dense batteries with diamond battery technology (https://en.wikipedia.org/wiki/Diamond_battery).
Wants nothing more than to erupt volcanoes.