Master Virgil:
You need your own coffin to perform the second trial, the Ritual of the Red Coffin. Yes, I'm speaking of the coffin you use to bury an elf when he dies. According to the funeral customs of the Dark Elves, we need a traditional coffin made from the carapace of a beast. You must make this yourself.
You should ask Abyssal Celebrant Kalinta how to make a coffin. You can meet her if you go to the Dark Elven Guild of the village of Gludin. You must take this letter with you.