Fungal Amalgamation
It is a being entirely comprised of the Infection, every phase it adds bug parts to itself to gain extra attacks from those bugs. Ants would add an acid attack, Beetles would add the rock throw, Bees or Dust Mites would have pollen or dust. Beating it would give the "Fungal Infusion" mutation, increasing defense of armors made from the bugs it uses to gain attacks. (Ant armor, Bee armor, added Beetle armor?)

Great idea!

I think it might be interesting if you have to defeat it to plug the haze, just an idea.