I've made a lot of progress on my first boss creature. You will face a large sewer mutant that summons tentacles and shoots blobs at you.
I was able to program the boss's movements using a script in the XML file that loads code on startup. My program deciphers the parts of the functions from the text and uses reflection in C# to run things from inside the program. Here I am able to set the position of my boss and have it summon tentacles in certain points on the pre-made building.