Weapon (glaive), very rare (requires attunement)

You gain a +2 bonus to attack and damage rolls made with this magic weapon.

This is an Ondregoran artifact of unfathomably ancient origin, likely with mysterious and unknown properties.  It appears to have been created for a specific purpose for a great future champion of Ald Faerth.

The weapon is fashioned from a mysterious, golden-hued metal of Ondregoran origin known as rhaele.  The shaft is precisely and intricately engraved with geometric designs in intertwining patterns.  The patterns can be observed to entwine in smaller and smaller progressions the longer you study the mysterious markings.

Stormcaller can temporarily absorb one element: acid, cold, fire, lightning, radiant, thunder.  When an element is contained within the weapon a dark crystal at the base of the blade glows and swirls with light, a visible effect of the elemental energy within; perhaps roiling with red hot flames or boiling with corrosive acid.  Whenever an element is present in the weapon it deals an additional 2d6 damage of the same type. 

As an action, you can expose Stormcaller to an elemental source and absorb it into the weapon.  The source can be natural, such as a bonfire or a frozen lake, or it could be a magical effect, even a spell.  The weapon is never damaged by exposure to the elements, although you may suffer the consequences when exposed to such dangers.  If Stormcaller damages an elemental creature you can use a bonus action to absorb its element type into the crystal.  There is no limit to the number of times you can change elements, but 24 hours after the first element is absorbed the energy fades and the crystal becomes dark until an element is absorbed again.

In addition, Stormcaller can cast the Thunderwave spell (save DC 17) as a 3rd-level version of the spell once per day.  This ability recharges each day at dawn.

Elemental Tempest (conjuration)

Casting Time: 1 Action
Range: 120 feet
Components: M
Duration: Concentration by wearer of the Aelder Storm Circlet, up to 10 minutes

When Stormcaller contains elemental energy, you can take your action to release it from the crystal into the air above you. A storm cloud forms in the shape of a cylinder that is 10 feet tall with a 60-foot radius, centered on a point you can see within range directly above the weapon. The storm cloud may take some time to coalesce, during which the weapon does no additional damage to melee attacks. The ability fails if you can’t see a point in the air where the storm cloud could appear (for example, if you are in a room that can’t accommodate the cloud).

When the storm cloud is complete, choose a point you can see under the cloud. A bolt of elemental energy matching what was in the crystal flashes down from the cloud to that point. Each creature within 5 feet of that point must make a Dexterity saving throw. A creature takes 6d10 damage on a failed save, or half as much damage on a successful one. On each of your turns until the storm ends, you can use a bonus action to call down the element in this way again, targeting the same point or a different one.

The storm can be ended at any time, but the elemental energy in Stormcaller is depleted. The storm must be ended before an element can be absorbed again. Only one storm can be summoned per day. This ability recharges each day at dawn.

Aelder Storm Circlet

When worn by an ascendant Aelderblood, the Circlet telepathically links you and the wearer over any distance on the same plane of existence.  This communication can be activated or blocked at will by you or the wearer.

As an action the Aelderblood can invoke the primal elements to fill the crystal in Stormcaller.  The wearer must succeed at a Charisma check (DC 12) to invoke or change the element.  This can be done over any distance when the telepathic link is active.  The ability otherwise functions the same as the weapon’s ability to absorb elements.  The wearer can invoke or change an element up to three times per day and regains this ability after a long rest.

To conjure the Elemental Tempest, the wearer must succeed on three Charisma checks (DC 12). The successes don't need to be consecutive; keep track until the wearer collects three. A die roll of 20 on any check will cause the storm to instantly appear; a die roll of 1 will cause the ability to fail and the elemental energy in Stormcaller is lost. The Aelderblood circlet wearer must concentrate to conjure and maintain the storm (for up to 10 minutes).

Additional abilities and properties may be discovered with these artifacts in time.

Proficiency with a Glaive allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Damage: Melee Weapon Attacks, Combat, Heavy, Reach, Two-Handed, Graze