This chapter is a complete guide for The Guardian of the Underworld quest. Here you will find a walkthrough, as beneficial as possible, for this side quest.
Spirit Iron Fragment x6
Smithing Text: Yokai Water Pot
Young Onmyo Mage's Locks x1
Wind Amulet x3
Amrita - 3384
Gold - 12000
This mission takes you to a small arena where you have to face various Yokai. Before you start the quest you can face a few Revenants that has died during this mission. The fact that this mission is a combat trial means that there should be a lot of summoning signs.
It is important to have a charged Living Weapon and use it when in need. Below, you can find information about the enemies that you must defeat in particular stages. The important fact is that the breaks between the stages are so small that you won't even notice when the happen. In practice, this means that you have to fight for a few minutes.
Stage 1: In this stage you must defeat a single dweller. He is not different than the other ones.
Stage 2: You must face a dweller again. What is interesting is that when you approach the water then, during stage 2, the third stage will begin.
Stage 3: Two dwellers and Oni-Bi. Remember that low stance is the best for dwellers. When you use it you are sure that most of your attacks will hit the target.
Stage 4: Giant dweller. Greater variety of attacks and bigger damage. It can spit poison at a distance which means that it doesn't even have to jump at you to inflict poison.
Stage 5: Oni-Bi and two Yoki. Use the monument in the arena to provoke 1 vs. 1 fights. First, defeat Oni-Bi because its projectiles are very irritating.
Stage 6: Two Oni-Bi, One-Eyed Oni and One-Eyed Imp. Try to ignore the Imp so he won't turn into the giant one. Avoid One-Eyed Oni's attacks and eliminate both Oni-Bi. Then, eliminate Oni and deal with the Imp as the last enemy unless you can defeat him in one combo. It is important to not use a single attack on him because this can trigger his transformation. If you previously tried to use the monument then you should know that One-Eyed Oni can destroy it with one swing.
With the end of the final stage, the mission is completed. You can go back here at any moment to get some Amrita.