A black orb has appeared in the Vault of Tears, driving the resident creatures wild... Go and investigate!
This bounty is available to complete after beginning Errand 131.
Unlike with Aapep, Burden ISN'T something you want to use in this fight; instead, focus on blasting him with Astra from the edge of the field while your other party members deal with him up front. Death Rattle will inflict curse, just like before, but since you're using magic primarily, it should not affect you in the least. Black Bolt and Serpent Strike will do a decent amount of damage though, so keep an eye on your party's HP, just in case Esther needs some assistance.
If firing off magic bores you, then feel free to rush in and attack; just be ready to heal more often.
Defeat it and you'll complete the bounty hunt, return to the Swift Solutions to claim your reward.