Aegis of the Earth Mother

The Aegis of the Earth Mother is a legendary shield of volcano forged stone. It is surprisingly light, no heavier than a regular shield of its size, and gives off a light heat to the touch.

Abilities
The wearer gains a +2 bonus to AC when using this shield and has resistance to thunder and lightning damage. It has the following additional properties:

Warden of the Mountains
In the presence of Elemental Air the Aegis of the Earth Mother glows with a dark orange light and gives off a great deal more heat, yet causes no pain or damage to the wearer. While glowing, the shield gives off dim-light up to 30 feet and the wearer has advantage on attack rolls against Air Elementals and Air Genasi. Additionally they can attack with Aegis of the Earth Mother as a bonus action to cause 1d4  bludgeoning damage and 1d6  fire  damage on hit. The wearer does not add their proficiency to the attack or damage rolls when attacking with Aegis of the Earth Mother in this way unless they have the  Shield Master  feat. The target must make a DC 10  Constitution  saving throw or be set aflame causing 1d6 fire damage at the start of each of their turns until they or an ally use their action to put out the flames.

Stone Armour
As a bonus action the wearer can expend 1 charge to increase their AC by 1 for 1 minute. Their armour and clothing become stone. If they are not wearing heavy armour already their armour and clothing becomes heavy armour, requiring proficiency and granting them the same AC as if they were wearing plate.

Stone Skin
As a bonus action the wearer can expend 2 charges to increase their AC by 5 for 1 minute and grant themself advantage on Constitution rolls. Their skin becomes hard stone, halving their movement speed and giving them disadvantage on Dexterity checks.

Stone Heart
As a bonus action the wearer can expend 3 charges to increase their AC by 30 at the cost of their  Dexterity  modifier to their AC until they dismiss the effect with a bonus action. Their entire body becomes a granite statue. While under this effect the wearer is immobile, immune to disease and poison, resistant to all forms of damage and cannot attack or take any action other than to dismiss this effect, use a Divine Spark Miracle or activate  Stone Warden.

Stone Warden
As a reaction the wearer can expend 1 charge to cast the  Shield  spell on themself or any creature they can see. If they cast it on another creature the spell works as if they were casting it on themself.

Charges
Aegis of the Earth Mother has 5 charges that recover at midday. The first time each day that  Warden of the Mountains  is activated Aegis of the Earth Mother gains an additional charge, up to a maximum of 6.

History
The Earth Mother has long been an enemy of the tribes of Uut. However, this item was recovered from the Foerender, an Uutish champion. It is not known why she would have seen fit to bestow such a mighty gift on an enemy.