Kalinta:
I welcome you in the name of Shilen, child of darkness. So you are a Palus Knight in training who received the Trial of the Red Coffin from Master Virgil.
To complete the trial, you must make your own Coffin of Eternal Rest. This is not the crude wooden coffin, made by humans to bury their corpses in the backyard of their temples. This is a traditional Dark Elf coffin made with the carapace of a beast and the silk threads of a spider. The materials needed to make this coffin are all very rare, and the process of searching for the materials itself is a part of the trial. Therefore, you must find the materials yourself.
Ask about the materials