I've been on the hunt for them, and I can't find the answer to this question online. Do the new Necrom triptych paintings drop in treasure chests like the other new paintings, or do they drop from a separate source like safeboxes?
One of the people in my trials group got one to drop from the chests in Sanity’s Edge trial. Don’t know about overland chests but I think they probably do, it’s just a low drop rate.