The Mighty Mountain Kings are warriors who are able to channel their ancient heritage into their fighting form, and are able  Generally, the mountain kings live for the thrill of battle, and the desire to overcome the toughest foes.

Restriction: Dwarves Only

Only the Dwarves have spent the time and energy to pick up on the power that Mountain Kings can wield, and as such are the only ones shown to be able to utilize the power.

Storm Bolt

When you pick 3rd level, you inherit the innate magnetic prowess of ancient dwarven champions. Once per turn, you can spend a point of rage to throw a weapon held in your hand, making a ranged attack roll up to 20 feet away, 40 feet at disadvantage. The weapon deals normal damage on a hit and immediately returns to your hand afterwards, hit or miss.

When you hit with this attack, you may optionally spend additional points of rage up to your proficiency bonus, to deal an additional 1d6 lightning damage per point of rage spent. If the target is not immune or resistant to this lighting damage, they must make a Constitution saving throw versus your Rage save DC or be stunned until the end of your next turn.

King's Grudge

Also at 3rd level, you inherit the pride of the ancient dwarven kings. Whenever a melee attack of any kind is made against a target other than you within 30 feet, you may spend a reaction to goad the attacker and gain a point of Rage. That target must make a Wisdom saving throw against your Rage save DC or the provoking attack will have disadvantage, and any further attacks that the attacker makes not directed at you will also have disadvantage, until they successfully strike the Mountain King, or the Mountain King strikes the target, whichever comes first.

When either of these happen, the Mountain King gains an additional point of Rage. The enemy cannot have disadvantage on melee attacks against the Mountain King while under this effect.

Avatar

At 7th level, you inherit the blood of ancient dwarven guardians to triumph over interlopers. As a bonus action, you unleash a battlecry and grow, as if affected by the Enlarge part of the Enlarge/Reduce spell, as a supernatural ability, lasting for 1 minute. While in your Avatar form, your skin hardens and grants an additional effect depending on your subrace:

Ironforge; Your rocky skin grants you resistance to slashing, piercing, and bludgeoning damage.

Wildhammer; Your metallic skin surges with lighting, dealing 1d6 lighting damage to enemies who strike you within 30 ft. You may spend points of rage when this damage happens to increase the damage by 1d6 per point and provoke a Rage save DC versus stun, as if empowering a storm bolt, again up to your proficiency bonus.

Dark Iron; Your molten skin radiates a blazing fire, dealing 1d8 fire damage to enemies who start their turn within 5 ft. of you. You gain temporary HP equal to this fire damage done, stacking up to your Warrior level.

You may activate Avatar once, and can do so again after a Long Rest.

Dwarven Athletics

At 10th level, you inherit the aptitude of ancient dwarven warriors. Unstoppable in your advance, you gain advantage on saving throws against abilities and effects that would reduce, limit or halt your movement while moving. This does not prevent you from being affected by difficult terrain while running.

Additionally, at all times, your jumping distance is doubled, and you can make long and high jumps with a 5-foot running start. You can make a jumping move to replace some or all of the distance of a Charge maneuver, effectively bounding with a pseudo-flying speed that forces you to land after the Charge attack resolves.

Power Surge

At 15th level, you inherit the magical power of ancient dwarven masters. Any time you would deal additional damage with a Mountain King feature, increase the dice value by one step (Spending 2 points of rage on a hit with a Storm Bolt will add 2d8 lightning damage, instead of 2d6, for example). Your Storm Bolt doubles in range, and you also gain a +2 bonus to your Rage save DC.

Blood of the Mountain

At 18th level, you inherit the awesome potential of ancient dwarven mountain kings of yore. Your Avatar feature can now activate with no action needed, whether or not it is your turn. If you are surprised, you may activate Avatar to negate the surprise round.

Avatar now grows you to a Huge sized creature, towering over the opposition and giving your weapons Reach if they do not have it already. The effects of racial abilities from Avatar double:

• Wildhammer's damage becomes 2d8 lightning (+2d8 per point of rage spent)

• Dark Iron's damage becomes 2d10 fire with a maximum cap of double your warrior level in temporary HP

• Ironforge dwarves become immune to slashing, piercing and bludgeoning damage.

You suppress the effects of Exhaustion while in Avatar. You may activate Avatar again on a given day even if you normally cannot. If you do, you suffer one level of exhaustion.