Geomancy

The Geomancer is a sorcerer that focuses on crowd control and disrupting enemy movement by destroying terrain around them. When threatened however, they won't hesitate to blast foes apart with geysers of burning magma. These kind of sorcerers are often descended from long lines of Dao and Efreeti, or have been taught how to tap into the grounds natural energy.

Thermal Born

Starting at 1st level, the heat of the ground warms your skin. You have advantage on saving throws to avoid exhaustion, you have resistance to fire damage, and you're naturally adapted to hot climates, as described in chapter 5 of the Dungeon Master's Guide.

Breaking Ground

At 1st level, as a bonus action, you can target a spot on the ground within 30 feet of you, breaking the ground in a 10ft radius sphere, upturning and cracking it. The affected ground is considered difficult terrain, and creatures within take fire damage equal to your class level at the end of their turn.

You can use this ability equal to your charisma modifier, and regain all uses at the end of a long rest.

Stone Guard

At 6th level, as a reaction when you are attacked, you can pull material from the ground around you. This material floats around you and guards against incoming attacks, raising your AC by 5 until the beginning of your next turn. 

You regain your use of this ability at the end of your next short rest.

Earthen Shackles

At 14th level, you gain the ability to shackle one huge or smaller creature to the ground with great earthen shackles. As an action, you can target a huge or smaller creature or object within 60 feet of you and cause massive shackles made of rock and earth to wrap around the target. The target must make a Dexterity saving throw against your spell save DC or be restrained for 1 minute or until you lose concentration. The target can attempt a strength check against your spell save DC at the end of each of their turns while restrained.

If the target is airborne when they are shackled, they are pulled to the ground, taking 1d6 of bludgeoning damage per 10 foot fallen.

You regain your use of this ability at the end of your next long rest.

Crack the Earth

Beginning at 18th level, you can channel the deep powers  within you in order to sunder the ground.

As an action, you channel the deep thermal energies within the ground in a 150 foot diameter sphere around you, causing cracks to appear in the ground, and geysers of lava to shoot out for 1 minute. As a bonus action on each of your turns for the duration, including during the turn you activate the ability, you can target one spot and cause a geyser of lava to explode out in a 15 foot wide, 100 foot high column. Any creatures caught in this blast must make a Dexterity saving throw against your spell save DC, taking 10d6 fire damage on a failed save, or half as much on a successful one.

You regain your use of this ability on a long rest.