Aldebaran

Aldebaran is a Stage IV Gastrea that appears during the Third Kanto War arc. It is named after the brightest star in the Taurus constellation, due to the fact that it was known as the "right-hand man" of the Stage V Gastrea Taurus, during the early years of the Great Gastrea War. They were infamous for organized attacks in parts of the Asian continent, with Taurus being near-invincible and Aldebaran being able to secrete pheromones to control the other Gastrea. After Taurus' defeat by the IP Rank 1 Initiator, Aldebaran reappeared during the Third Kanto War arc and latched itself onto Monolith 32 and injected Varanium corrosion fluid into the Monolith, destroying it within a few days. It then lead an organized attack of around 2000 Gastrea against the military and civil officers of Tokyo Area, leading to the commencement of the Third Kanto War.

Along with its pheromone secretion and its corrosion fluid injection ability, it also regenerates at an unbelievable rate.