Thank you @Mellowochi! ^^
Afer looking at this a lot, I decided to finally call the illustration finished.
I was thinking about what kind of storytelling elements I could possibly place into the drawing. Since I wanted the scene to be easily readable, to keep it simple and have it not too crowded, I just added some minor elements: I added some fight marks to the wall, some damage caused by Isaiah's weapon, small hints of what has happened there. His magic is spreading around him, showing his takeover and his negative influence on the place.
Thoughts and opinions would be still very welcomed!