Treasure demons are rare personas that sometimes appear when you steal a treasure in a palace or open a chest in Mementos. They look like diamonds, attack them before they run away. They are immune to most attacks and leave after a turn or two has passed, but if you down them you’ll be able to obtain them without any negotiation. Killing them will give you a good amount of exp and gold, but you should grab one to register as they come with a lot of different abilities which are useful for fusing. You need to catch all of them for a trophy, and they also count towards your persona compendium completion. They can also be transmuted with Black Rocks to create accessories, some of which are very powerful.
They appear in palaces and Mementos, they appear more frequently in Mementos when the weather is abnormal. Crafting a treasure trap (2x yarn,3x plant balm, 1x cork bark) will make them spawn more often, these last until you quit for the day. Best way to find them is to go explore a floor in Mementos that they spawn on with a treasure trap active, if they’re not there just go up a floor and go back down, that floor resets and you can look again.
The lower level treasure demons have weaknesses that can be exploited, the higher level ones don’t have weaknesses and you’ll have to down them with a critical strike. Personas with lucky punch and miracle punch are needed for to accomplish this, or you can stack +luck on characters and pray for a critical strike with a melee attack. Abilities that increase crit such as Rebellion and Revolution will help, but they do not stack with the Apt Pupil passive. Morgana is a good member to bring because he learns lucky punch. Easiest way to down the harder demons is to use the Tower Arcana’s Down Shot ability which guarantees a crit, provided it doesn’t miss.
Regent – Level 10 – Weak to Psy and Nuke damage. Found in the second Palace and Path of Aiyatsubus and Chemdah in Mementos. You’re guaranteed to run into one as part of the tutorial.
Queen’s Necklace – Level 15 – Weak to Gun. Found in the third Palace and Path of Kaitul in Mementos.
Stone of Scone – Level 20 – Weak to Curse. Found in the fourth Palace and Path of Akzeriyyuth in Mementos.
Koh-i-Noor – Level 25 – No weaknesses. Found in the fifth Palace and Path of Adyeshach in Mementos.
Orlov – Level 30 – No weaknesses. Found in the Sixth Palace and 1st-6th levels of Path of Sheriruth in Mementos.
Emperor’s Amulet – Level 35 – No weaknesses. Found in the seventh Palace and 7th-12th levels of Path of Sheriruth in Mementos.
Hope’s Diamond – Level 40 – No weaknesses. Found in the seventh Palace and 12th-13th levels of Path of Sheriruth in Mementos.
Crystal Skull – Level 50 – No weaknesses. Found in the seventh Palace and 12th -13th levels of Path of Sheriruth in Mementos.