This dark blue obsidian amulet in the shape of the Infernal scripting word for aegis, a twisted square with two lines coming out of it that extend into crosses; keeps its wearer warm at all times, and faintly hums with otherworldly whispers of guidance.

While wearing this amulet, you have immunity to fire damage and are immune to the effects of extreme heat, as described in the Dungeon Master’s guide; and immune to any negative effects caused by warm weather.

In addition, whenever you deal fire damage to a hostile creature, the amulet gains one charge, up to a maximum of 4 from a single source (if you cast the Fireball spell and you deal fire damage to 8 creatures this way, you only gain 4 charges rather than 8). It can hold up to 18 charges, and the number of held charges reset to 1 when you finish a long rest.

You can use stored charges to perform either of the following effects:

• When you are reduced to 0 hit points, you can use your reaction and expend 4 charges to cause hellish energy to flow through you and allow you to resist death. You regain 1 hit point, and the creature that reduced you to 0 hit points must succeed on a Constitution saving throw against your spell save DC or take fire damage equal to your level + your Charisma modifier, taking half as much on a successful save. You gain temporary hit points equal to the amount of fire damage dealt this way.
• Whenever you deal fire damage, you may expend any number of charges (no action required). The source of the fire damage deals additional fire damage equal to a number of d12s totalling the number of expended charges, and if the creature is immune to fire damage, it is treated as resistance instead.
• As an action, you may cast a spell from your subclass’ expanded spell list without expending a spell slot. To do so, you expend a number of charges equal to the spell’s level.
• As a bonus action, you may expend 7 charges and restore an expended warlock spell slot.

Notes: Immunity: Fire