Mega Terrors
To the Indigo Caste, they are Gods. To each other, they are rivals. To the universe? They are the End.
Mega Terrors are simply the name they've been classified with. In truth, these horrorterrors are the vastly intelligent, incredibly long-lived adult form of the tinyterrors. They make their home in the forth dimension, where other dimensions and universes are like flies to brush off or use as they will. The trolls' universe is simply an idle distraction to these beings, a game that they play to pass the time, though as of late it has become more interesting to many of the oldest of these beings.
They are not used to resistance, or even being known about enough to have a resistance formed. This amuses them.
To say it is possible to kill one of these beings, or even to thwart their plans, is like saying it's possible to move a sun with one's bare hands. The chance that it would succeed, especially without leaving those that attempt as much as a burning pile of ash, is so miniscule it might as well not exist. Even alone, they are a massive force to be reckoned with. Their abilities allow them to manipulate what the trolls sense as space and time, giving them the appearance of being in multiple places at once, or even partially here and there, twisting and breaking reality as they see fit.
But despite this, these beings are incapable of entering or manipulating anything within the third dimension. They are so firmly rooted in their own dimension that the act of trying to force their vast and complex bodies into such a restricting space is simply not possible. So they must watch from afar instead, and use their avatars as their means to their ends.
If they did find a way to enter the trolls' universe, the destruction that would be wrought could only be likened to the apocalypse.