Makuta Toxic wasn't all just Toxic, he once a lieutenant in Teridax's armada . Until he was assigned to raid arka nui , but in the process , he needed a host , once absorbed a matoran for a host , the matoran in the process died , leaving him in a solid state. until he was arrested by the Toa Arkada and New Arkada , and was sent to the Pit . Changing his darkness to pure poison . Then he was trained by Kalmah for underwater combat . Then returned to Arka nui for revenge. He then made the BoD , Battalion of Darkness
His shoulder armor which I would thank Scott Tyler ( Scotttjt in Youtube) for inspiration .
His spear can dissolve anything into a sand like state leaving only the mask and it's weapon/s , it can be cured IF the particles ( each one) are all together and if you place them in protodermis.