Preemptive Design
I started out with a loose sketch developing a boss scenario using some core ARPG mechanics allowing the player to move between platforms and use LOS in order to evade large area abilities
mechanics
Projectiles
Evasion
Advanced Locomotion (Mantle/Slide Control)
Establishing gameplay
After I finished the loose sketch I prototyped it using BSP to test scale/pacing/and camera position in order to verify the gameplay components.
Extended
Once I was happy with the general progression of the player character I moved towards dynamics lighting and loot trying to better guide the player throughout the level.
I ended up pushing back some of the walls as they were a little too narrow to free up a little more camera space prior to moving to lighting, after that I added particle FX as well as further environment dressing meshes for a final pass.