Looks great so far. I like the silhouette and the spikes at the top. Some feedback... try adding more variation to the bricks (like cracks and worn edges) because right now a lot of the bricks are the same size. You have the right idea with trim.. like the crumbling bricks etc. This is great start! Keep going. :)
I tend to make spline outlines in max to test the repeat before I take 5 or 6 bricks into Zbrush and go nuts. I always export a teselated plane behind the extruded splines and ensure the bricks are at slight tilted angles. That way in zbrush i have bricks and the grout between them being modified together for a more…