Syenite is the final secret level of Obsidian, which is also accessible from the final level, Gaussian Blur. This can make the task much easier. There are more than a few heavy weapons in this level, but you still have to find out how to get them.
Mission Statistics
None specified, but you would want to obtain as many earthshakers as possible. Leave the Cloaking Devices and Invulns for the boss(es).
None
