As your connection to your warlock grows, you've gained the ability to detect and manipulate those who desire destruction. As an action, you can force any humanoid with destruction in their hearts, within 60 feet of your warlock, to make a DC 20 Wisdom saving throw. On success, they resist your influence and immediately turn hostile to your warlock. On failure, you possess them and take control of their body for 1d4 hours. You gain access to their stat sheet, knowledge, and any abilities or items they have.
Avatars, those marked by Fears other than The Desolation, and those without destruction in their hearts automatically succeed the saving throw.
Regardless of success or failure, this ability can't be attempted again until after 1d4 long rests.
Glimpse of Desolation: You can use a bonus action to peer into the heart of a humanoid within range, and determine whether they can be possessed.
Mischievous Presence: The only immediate signs of possession are fire-red eyes and a rapidly-increasing body temperature. For the purpose of detection spells such as Detect Good and Evil, your vessel will count as both their original race and Fey.
Ashes to Ashes: The longer you possess a body, the greater the physical toll on your vessel. As the hours tick by, the body will grow increasingly charred and fragile, and begin to smoke. If you choose to depart the vessel before the duration is up, they take 1d6 fire damage for every hour you've possessed them. If you remain in the vessel for the full duration, they will crumble into ash.
In addition to the vessel's attacks and spells, you also gain the following spells when your warlock reaches the indicated total level. You have a number of spell slots equal to your warlock's proficiency level. Each spell regardless of level, including those that would normally be cantrips, use a single spell slot. For spell saves and spellcasting ability modifiers, use your warlock's.
As an action, your vessel can be immediately destroyed in a fiery explosion. Each creature in a 20-foot-radius Sphere around you makes a Dexterity saving throw (against your warlock's DC), taking 8d6 Fire damage on a failed save or half as much damage on a successful one. Flammable objects in the area that aren’t being worn or carried start burning.
This ability pleases The Desolation, but uses up a great amount of your power on the material plane. If you use this ability, add 2 long rests to the counter before you can attempt your next possession.