The Cursed Canvas - Altissa
First Available: Chapter 9
Other Requirements: Complete The Pen is Mightier than the Sword
Rewards: 4,000 EXP & 20,000 Gil
Once you've completed The Pen is Mightier than the Sword from Vyv in Lestallum you'll be able to accept the final quest in this chain, The Cursed Canvas. This quest is a bit weird considering once you complete it you can't turn it in unless you use the "go back in time" feature at any Inn.
The first thing you'll have to do for this quest is head over to the Diner in Altissa and speak with Warkam here; he gives you a Hunt which is required for this quest. He'll also put a quest marker on your map for The Cursed Canvas and update your quest. The location we need to visit next to trigger the event for this quest in the southeastern portion of Altissa, the same location you see me standing at in the map screenshot below and in the screenshot above.
At this location you'll find a guard standing out front of a staircase which leads down into a basement area. In the lowest portion of the basement (after you run past the containers filled with magic) you'll come across the boss, Lakshmi.
For this quest technically all you need to do is take a picture of the painting with Prompto - you can actually run away from the boss and not even fight her. However, fighting her is the best approach that way you can complete the Hunt as well as this quest.