In the future, scientists created a microorganism that would naturally decompose the toxic materials that were poisoning the Earth. They altered the genetic makeup of strains of flesh-eating bacteria so it would eat only the toxins but ignore living tissue, so it could be unleashed to destroy the poison without hurting complex life forms like humans. The scientists couldn't contain the bacteria (now called The Mandate) outside of the lab so they created organic orbs in which to store and transport it. That's when things went bad. The genetic mutations had actually allowed The Mandate to develop sentience. After sentience, The Mandate desired a body, so they shaped themselves into a bipedal creature. Now independently mobile, The Mandate used their toxin and flesh eating properties (which they had kept hidden) to destroy everything in it's path. In days the single original Mandate had wiped out the city where it was created. Then it started to multiply. The original, called the Primogenitor, was capable of producing offspring and they quickly started showing up all around the world. By the time the rest of the world new the danger, it was already to late. They developed Anti-Mandate Armored Corps (robots with armor and ammunition made of adamantium) to fight the Mandate, but the adaptive abilities of the bacteria was too much for them to combat.
Each Mandate has an orb-core that produces an enzyme that lets it maintain it's body. This allows it to regenerate and repair any damage almost instantly, making it unstoppable while the orb-core is intact. Not only that, The Mandate are capable of altering their physical form in any way imaginable, from creating wings for flight to energy weapons with limitless ammunition. The only thing that can stop the Mandate is adamatium since only adamantium can pierce the orb-core.