gaint monster ?

Ummm all over the map rly..Okay u need to do the Warsworn quests they will pair you up with an warsworn who dies and you will fight for you first time with that Niskaru Tyrant in a cave.That will be the mission where you start from warden bridge to seek a killer who is a niskaru hunter.

If i tell you it will be a spoiler.Yes it is a large boss at the end but befor it you will face an Niskaru lord in the Mel Shiantir (i think that is the name) second part of the map and game,one big huge one eyed thing.Lesser boss like etin,dead kell from dlc,(didnt played the dlc teeth of naros),winter fae are present in the game they arent as strong as the Balor boss but they will give you hard time to kill them,a tough boss will be Octienne a....gnome lol he is hard to kill but with chakrams or bow he is easy to find.But only Balor and the last boss are huge from what i know but dont worry there are plenty of your size bosses in the game size i mean each will gave you nice a nice option to fateshift and kill them in different ways.A and NP.