Avoid optional battles and hurry!

In this mission, you spend the most time activating wall devices and traveling from place to place to collect Orihalcon fragments. Sacrificing your clear time will affect your Devil Hunter rank, so it's wiser to clear the mission ASAP. Fortunately there aren't many compulsory battles, so you can simply ignore the other enemies. However, do be careful not to get caught by the Arachne's web and get delayed or dragged into battle.
 

Grab all available red orbs for the taking!

If you've chosen to battle as little as possible to reduce time consumption, you probably won't be receiving enough orbs from defeating enemies. To compensate for that, remember to pick up all red orbs that are freely lying around. There's a red orb crystal in Forbidden Land: Front, and free red orbs in Gears of Madness and Top Subterria Lack.

In this mission, you will be seeing a lot of tri-colored doors as on the top left picture, and wall devices as on the top right. The tri-colored doors will lead to a different room everytime you activate a certain wall device once. Activating a wall device one more time after it's been activated will yet bring you to a different room, so unless you want to get lost in this mission, follow carefully the number of times you need to activate the wall device.

You start the mission in the Gears of Madness room. You will then reach the Altar of Evil pathway where you see giant blades creating an obstacle for you. Get to the end of the corridor while carefully passing the blades and you will receive your first Orihalcon fragment. You can use Trickster's Dash to easily and safely pass the blades. Be careful of the Soul Eaters (Dullahans in DMC3SE) who try their very best to annoy you. When done, go back to Gears of Madness and activate the wall device you see here once. Then go through the tri-colored door.

Now you should be in the Rounded Pathway where Dullahans float around. Keep going to the end of the pathway until you reach a door. Enter the room to find your 2nd Orihalcon fragment. Be careful of the Arachnes that will appear here and leave the room. You will find another wall device here outside the room to your right. Activate it once and leave the Rounded Pathway where you came in.

Now you will be in the Top Subterria Lack. Run past the wall device you see right near you until you see a bluish door. Enter it to find yourself in a smaller Rounded Pathway with Soul Eaters (Dullahans in DMC3SE) and a green orb. You can use Trickster's Sky Star to easily pass the floor blade obstacles. At the end of the pathway you will find your 3rd and last Orihalcon fragment. Leave this room and activate the wall device outside twice to proceed to clearing the mission.

Go grab a blue orb fragment!

If you want to obtain a blue orb fragment, activate the wall device in the Top Subterria Lack only once, then enter the tri-colored door. You should find yourself in the path to the Underground Arena. Jump to the bottom of the arena and circle it a bit to find a blue orb fragment lying on a boulder. To proceed with the mission, go back where you came from and re-activate the wall device just once more. Then re-enter the tri-colored door.

Hard mode

The enemies remain the same as normal, but they are faster in speed and are higher in defense. Try to battle only when needed and hurry on to collect the Orihalcons fragments.

Dante Must Die mode

Enemies remain the same but they're even stronger than before. They tend to interrupt your movements and it may be harder to progress. In such cases, you may want to finish them first.

Heaven or Hell mode

Be careful of the enemies since they move around quickly. And of course, also be careful with the traps and obstacles. You may want to stick with Trickster to make things easier for yourself.