The third stage in the castle isn't terribly remarkable, but you may still find yourself short on life when you reach its end thanks to the giant stomping robots in the last few passages.
When you first appear, you should immediately switch weapons to the shadow blade. There's an enemy directly overhead, so jump up and toss a blade or two its way and you'll put it out of commission. With that tended to, Rush Coil up to the ledge it occupied, and from there hop left. You're now standing below a ladder. Switch back to shadow blade, then climb up the
ladder into the next room. There, hit another enemy from below with the blade. Now switch back to Rush Coil and spring up to that ledge, and from there hop right and then back left to the ladder suspended from the top center of the screen.
At the top of this ladder, slide under the space to your right and collect an energy tank. Then slide back left and use the Rush Coil ability to get on top of that ledge.
From here out, you'll only need to be armed with the regular arm cannon. Work your way right and you'll see various bulbs in various recesses. Drop down to their level so that you can take them out as you go, and work toward the right. The grenade-shaped robots are in evidence, as you might have expected, so be sure to take them out with your arm cannon before they get close enough to cause you harm.
You'll soon reach the right edge of the room, where you can drop down a pit. Do so, and fall straight down, past where a projectile-slinging robot waits. Drop down the new opening on the screen's left side, and you're halfway to the end of the stage.
Now you need to work to the right, past two giant, stomping robots. It's hard to slide under them without suffering damage, as they're so huge and the space is so small. Try and take them out first, but make a run for it if you suffer a hit.
Beyond the two robots, a ladder leads up to the next room. Here, you will see a ladder near the top left side of the screen. Spikes line most of the floor. To reach the ladder, you must hop up moving ledges and ride to the ladder. It's not terribly hard if you move quickly and get a feel for the speed at which they move. The next room is more of the same, and after that you'll find yourself in a new room with some item canisters above.
Use the Rush Coil ability to spring up to that platform and collect the goodies in the canisters, then drop back down and head right through the door that leads to the boss encounter.
NEXT: Stage Four