Best advice here is to grenade-spam the gunship you encounter early on foot (it takes 8) and then use the first sword powerup to rush pash the shield-weilding grenedier and the turret. Grab second sword powerup, hop the chasm (watch for stupid hopping bug things), toss a nade at the big robot, the second to last platform seems to give the best angle and won't trigger his attack. Use second sword powerup to quickly finish off Geist. The following elevator section has three enemy segments as ypu decend and the levels last boss at the bottom. Make good use of your grenades in these enemy sections to quickly finish them off, you won't need them for the boss. Once you reach the bottom, quickly slice the bottom ring-cannon 10-ish times to take it out, follow up with the middle ring-cannon on the right using swift jump attacks (at this stage its a good idea to hang out on the far right side) and being careful not to get hit by the laser that fires on the bottom. Finally use the platform to take out the last cannon as quickly as you can. This one's a bit tricky, but it's not too bad once you get a flow going, the top ring-cannon is definitely the most problematic and time consuming to eliminate.