Deep in the Amazon jungle, there exists a fungus the spores of which embed themselves in the brains of ants and take control of their minds, compelling them to seek out a location with the perfect amount of sunlight and moisture for the fungus to thrive. Once the ant is in position, the fungus kills it and grows out of its corpse, ready to produce more spores and take over the minds of more ants.
Endbringer evolved directly from that fungus.
In itself, Endbringer is a Sorcerer with unexceptional attack power, and very weak Defense. But once its Mana bar fills, it can pose an extremely serious threat. It takes control of the nearest enemy and forces them to switch sides for 8 seconds, which is plenty of time to inflict a lot of damage to their own team. While undeniably powerful, this is not a flawless strategy. Considering the time Endbringer needs to power it up, there’s a reasonable chance that it’ll seize the mind of an enemy who’s low on health and won’t survive 8 seconds.