As soon as you start in the hallway you fought Gigapede before, you are surrounded by some Blood Goyles. Take'em out to unlock the door at the top which you came from.
Take the door on right to get back to The Devils Tower. On top of it, on the side of the window is a mechanism
in which you have to use the Wheel-Gear you got from the jester. This
will move the blocking stones some levels below.
After they are moved, go there
to find a fork thingy called Vajura, take it and enter the Blue Door.
Kill the Hell Prides, go into the door at the top of the stairs. In the room,
jump upon the ledge on either sides of the room and follow them to a
space in which a mechanism rests in which you can use Vajura. After
using it the cage on the stairs will be lifted, go there to find Soul
of Steel, which'll let you fly over the broken staircase which were opposite of the red door leading to Gigapede.
Activate the platform using the rune clock and fight your way through Hell Prides while going up. Be careful not to fall down as you'll have
to activate it again. After you've reached the top, follow the ledge to a Divinity Statue and some destructible objects for gaining red orbs. Go into the door to face a battle with a couple of twin ...
swords.
Hope that helped. And a small hint for the boss, try to lower their vitality equally, so that you can actually kill the 2nd guy almost after you killed the 1st
Oh and welcome to the forum as well^^