Due to various circumstances, you have become endowed with elemental power originating from the elemental plane of earth. Explain the origin of your newly awakened affinity; whether it is a divine blessing, the power of a bloodline, a strange coincidence, a deal with the (proverbial) devil, or some other fifth thing. Is it something you wanted? Did you have to sacrifice something to obtain this power? Has this elemental endowment brought about changes to your appearance or personality? If the source of your endowment isn't from the Elemental Planes, simply change the relevant narrative details to suit your character.

Elemental Physique

3rd level martial archetype feature.

Your flesh and soul are moulded by the primordial energies of the elemental plane of earth. Divination reveals your creature type to be both Elemental and Humanoid. You are immune to petrification, you are not slowed by difficult terrain caused by earth and stone, and your unarmored AC bonus is determined using Constitution instead of Dexterity.

Additionally, when you take bludgeoning, piercing, or slashing damage from nonmagical attacks that are not adamantine, the damage you receive is reduced by an amount equal to your fighter level.

Primordial Wisdom

3rd level martial archetype feature.

You are adept at reading the signs of the earth and you are fluent in Terran. You have advantage on any passive or active skill or ability checks made to identify abnormalities related to unworked earthen minerals.

You have tremorsense within 30 feet. This increases to 60 feet at 10th level and again to 90 feet at 18th level.

Endowment of Earth Advancement Options

You can choose one of the following options at 3rd, 7th, 10th, and 15th levels.

Earth Shattering Smash

Once per long rest as an action, you smash the ground with an elementally infused blow to incite earth and stone to burst out within a radius of 30 feet from you, turning the area into difficult terrain. You can choose to limit the radius, controlling it to be as small as 5 feet. The area remains difficult terrain until it is cleared or repaired.

Each creature within the area must make a Dexterity saving throw. On a failed save, a creature is knocked prone and takes 2d6 + your Constitution modifier of bludgeoning damage. On a successful save, a creature is not knocked prone and takes half as much damage. A creature that is already prone automatically fails this saving throw. Against buildings and stationary objects, this ability's damage is multiplied by your proficiency bonus.

The DC for this ability equals 8 + your Strength modifier + your proficiency bonus.

The damage and area increase at certain levels. At 7th level (35 ft., 4d6 damage), 10th level (40 ft., 6d6 damage), 15th level (45 ft., 8d6 damage), and 18th level (50 ft., 10d6 damage).

Fists of Stone

Your unarmed attacks have a base damage of 2d6 + your Strength modifier and they count as a +1 magic weapon. In addition, each time you hit a creature with an unarmed attack, its movement is reduced by 5 feet until the end of its next turn.

This magic bonus increases at 10th level (+2) and 15th level (+3).

Heavy Hitter

7th level advancement option. (Requirement: Strength of 19 or higher)

Your attacks are steady and mighty. Whenever you make a melee attack, you can choose to combine all of your multi-attacks into a single overwhelming heavy attack. When you do so, make a single attack roll which combines the damage dice and ability modifier damage of all your multi-attacks, adding 1d4 damage for each multi-attack. You have advantage on this attack roll. If the attack hits, you can shove that creature as part of the attack. If the creature you hit is reduced to 0 hit points, you can continue the momentum into an adjacent creature. The second creature uses its own AC against the same attack roll and, on a hit, takes any remaining damage and is also shoved.

If this attack is made with a two-handed weapon or if it is an unarmed attack, a creature you successfully shove is both pushed back 5 feet and knocked prone. Additionally, you can shove a creature that is up to two sizes bigger than you.

Mineral Carapace

7th level advancement option.

You can spend one hour grafting earthen minerals into your flesh, creating a mineral carapace that grants you a natural armor bonus. Removing or swapping the carapace takes one hour. You cannot wear armor while this carapace is fused with your flesh. The resilience of the carapace depends on the materials used to shape it. Creating a carapace requires at least two solid cubic feet of minerals for a medium humanoid, or one cubic foot for a small humanoid. The carapace does not need to be uniform and can take any form that doesn't impair movement. You can use normal metallic armor to create your carapace, converting its AC directly into natural armor. Natural armor does not impose penalties on movement, resting, or Dexterity (Stealth) checks. You can add your Unarmored Armor Bonus to your AC while donning the mineral carapace.

• Soft minerals (silver, gold, tin, etc.), AC 12.
• Common stone, AC 13.
• Sturdy minerals (granite, marble, common gemstones, etc.), AC 14.
• Strong minerals (crystal, iron ore, etc.), AC 15—16.
• Precious minerals (adamantine ore, refined steel, mithral, studded with gemstones, etc.), AC 17-18.
• Exceptional or magical materials* (refined adamantine, refined orichalcum, ruby, diamond, mineral materials from magical monsters, etc.), AC 19+.

Discuss with your DM to determine which AC is appropriate with which material composition. Consider what interesting properties might arise from using different materials. For example; a silver carapace might provide some bonus against creatures vulnerable to silvered weapons.

*Grafting magic rocks into your flesh might have some unintended consequences.

One With Earth

Once per day, you and all the equipment you carry can meld with a mineral object or earthen surface large enough to fully contain your body. Using your movement, you step into the earthen material at a point you can touch. Nothing of your presence remains visible or otherwise detectable by mundane or magical means. You can remain there until you choose to leave or until the area you are melded into is destroyed. If it is destroyed, you take any remaining damage from the hit that destroyed it and you are ejected from the surface, landing prone in the nearest unoccupied space.

While merged with the earthen material, the range of your tremorsense is multiplied by your proficiency bonus and you have a +10 bonus to your passive Wisdom (Perception). If you remain merged with the earth for the duration of a short or long rest, you gain the benefits of that rest.

Ripples in The Weave

Within the range of your tremorsense, you can perceive the echoes of magic within earth and stone. You are able to identify the presence of spells and magical effects that are tied to the earth. If it applies, you intuitively know the direction and distance of such effects. Additionally, you are able to vaguely estimate the intensity of the effect, whether it is dangerous, whether it is naturally occurring or artificial, whether it is native to this plane, or how old it is. This ability may require active or passive Wisdom (Perception) checks.

Rock Climbing

When climbing on a surface of earthen material, you have a climbing speed equal to your walking speed. You have advantage on ability checks or saving throws made to avoid being knocked off while climbing on a surface of earthen material. You have resistance to fall damage.

Additionally, if you fall and land on a creature or structure, it takes bludgeoning damage using the same damage roll as your fall damage but is considered vulnerable to that damage.
rocks fall and you die lol

Weight of a Mountain

(Requirement: Strength of 17 or higher)

As your flesh and bones become closer to stone, your weight is multiplied by 5; if it applies, this is in addition to any other weight modifiers. You count as Large when determining your carrying capacity and the weight you can push, drag, or lift. You count as one size larger when determining the size of creature you can attempt to grapple.

So long as you are on a solid surface or a surface of earthen material for which you have a movement speed, you have advantage on saving throws or ability checks against being grappled, restrained, knocked prone, or pushed back. Other creatures have disadvantage on attack rolls or ability checks that would apply these conditions to you. Whenever you are forcefully moved in any direction, the distance you are moved is reduced by half.

Note: Consider the negative implications of having +1000 pounds in a ~200 pound frame (with armor and equipment, it's likely much greater). For example, a marshy bog changes from difficult terrain into a potentially lethal sink trap. Most furniture can't support your mass. Old wooden floors might splinter with every step, including second stories, bridges, and vehicles. You'll sink like a rock even if a magical effect grants you a swimming speed. Not even an ox could carry you on its back. In most terrain, your footprints are impossible to conceal.

Earthen Body

7th level martial archetype feature. Choose one option from the Endowment of Earth Advancement Options.

Your flesh grows ever closer to that of a true earth elemental. You gain resistance to poison damage and you have immunity against being paralyzed or poisoned.

Whenever you are inflicted with thunder damage greater than your fighter level, you take 1d4 additional thunder damage.

Steadfast

10th level martial archetype feature. Choose one option from the Endowment of Earth Advancement Options.

You gain resistance to all damage received from sources that require Dexterity or Constitution saving throws. This does not apply to thunder damage.

The range of your tremorsense is increased by 30 feet (60 feet).

Inhuman Potential

15th level martial archetype feature. Choose one option from the Endowment of Earth Advancement Options.

The maximum of your Strength score is increased to 22. The maximum of your Constitution score is increased to 24. This does not increase your current ability scores.

Elemental Progression

18th level martial archetype feature.

Divination reveals your creature type to be only Elemental. You have resistance to bludgeoning, piercing, and slashing damage from magical and nonmagical attacks, but not from attacks by adamantine weapons. This is in addition to any other forms of damage reduction.

The range of your tremorsense is increased by 30 feet (90 feet).