How to get this quest
This quest is available in Nephlune's Adventurers' guild after completing Festival Of Greed.
Tracking the formula's owner
Go talk to the city's lord to update the quest's objective. Talking to Liliana after that is optional but lets you know about an alternative way to complete the quest.
Your goal is to take the drug formula from its current owner. This is the shady thug appearing in Trademond near the church when the day is a multiple of 5.
When you ask the thug for the formula, a fight ensues. The thug and his goons can deal a lot of damage, but they are quick to defeat if you have a slime companion, thunder-elemental damage and around 23 ATK. Begin by countering Stone Mind I and focus on the boss. Ideally, defeat the boss on turn 2 (he doubles all of his attributes this turn).
Delivering the formula
You can deliver the formula to Nephlune's white priestess or sell it in the underground city. If you sell the formula, you'll receive an inefficient alternate formula to give to the priestess.
Once you delivered either the original or the alternate formula to the priestess, report to Nephlune's guild to complete the quest.