BigRed

I really think he is meant to represent like, just a completely overwhelming overpowering enemy whose sheer physical presence conveys hopelessness. I think that goes with the general theme of that season and why the discovery of rainbow power was such a significant turning point. That being said , the scene where he is draining twilight sparkle of the combined alicorn magic in the everfree forest I think he's about 5x taller than she is, maybe let's just round him up to like 35-40ft max - but you. can clearly see that he grows significantly and substantially until from a distance he is so large he fills up the entire screen. I would say conservatively he is over 300-400 feet tall there, maybe as big as twice that, and I think the vantage point we see him stomping around in the distance and still feel the quaking of the earth under him he might be as far away as 1/2 mile or more. I think he'd be visible even that deep in the forest from ,say, applejack's house who isn't she supposed to live on the perimeter? Basically he is supposed to be a nigh-omnipotent god at that size with near absolute power