Geomancer

Geomancer
While all druids revere nature, it is a special sort that can harness the primordial energies of the world itself. The first geomancers were disciples of the great elemental Primals, harnessing the powers of the land and calling the dormant elements to their aid. Utterly in tune with the primal flows of energy, geomancers do not fear the darkest brambles or highest peaks - both, in equal measure, are their allies.

Geomancy
As they channel the divine might of the natural world, geomancers awaken the slumbering powers of the land around them. Beginning at 8th level, whenever you cast a spell of at least 1st level, you may manifest one of the following terrain effects on a number of contiguous 10' squares equal to the spell's level within 100'. No individual square can be subjected to more than one of these effects at once. You can always manifest the terrain effect attuned to their current biome, and can prepare up to two other effects. These effects can be exchanged whenever you take a long rest. If you are at least 13th level, you can prepare up to three other effects. If you are at least 18th level, you can prepare up to four other effects. Whenever a terrain effect calls for a save, use your druid spell DC as the save DC. All terrain effects manifested by this ability fade after ten minutes.
 * Acrtic: The terrain is shrouded in a terrifying whiteout of swirling snow, becoming both heavily obscured in a 10' high area and difficult terrain.
 * Coast: The terrain is flooded, floor dropping away into the tides. The ensuing pool of water is 10' deep. You can maneuver in this water as if you had a swim speed equal to your land speed.
 * Desert: The terrain is engulfed by shifting sands, becoming difficult terrain. Whenever a creature ends its turn on this terrain, you can forcibly move that creature up to 15', so long as they finish that movement on or adjacent to a square of shifting sands.
 * Forest: The terrain is covered in twisting, grasping vines, becoming difficult terrain. Whenever a creature ends its turn on this terrain, they must succeed on a Strength saving throw or be ensnared by vines, Restraining them. A creature may attempt to break free of the vines as an Action, making a Strength check against your druid spell DC, freeing themselves on a success.
 * Grassland: The terrain is soothed, and the deadly forces of nature placated for a time into pastoral serenity. Creatures on this terrain take no damage from and have advantage on saves against hostile terrain or environmental effects.
 * Mountain: Dark, ominous stormclouds swirl into being above the terrain, lashing the ground with wind and rain that inflict disadvantage on ranged attacks made by or against creatures within the area. Whenever a creature ends its turn on this terrain, they take Xd8 Lightning damage, where X is the number of damage dice inflicted by your cantrips. This damage is boosted by abilities which enhance cantrips.
 * Swamp: The terrain softens into a nauseating bog, becoming difficult terrain. Whenever a creature ends its turn on this terrain, they must succeed on a Constitution saving throw or be poisoned until the end of their next turn.
 * Underdark: The terrain is engulfed in inky blackness, becoming opaque and heavily obscuring a 10' high area. Whenever a creature ends its turn on this terrain, they must succeed on a Wisdom saving throw or be blinded until the end of their next turn.

Biome Attunement
The energies of the world flow around a geomancer, embracing them with their powers. Beginning at 13th level, you can ignore any negative effects of the terrain created by your Geomancy ability. In addition, if you have the Primal Wellspring class feature, you can cast the biome spells of any biome whose terrain effect you have manifested and are currently occupying. Finally, as an action, you can absorb a 10' square of a terrain effect created by your Geomancy ability, dismissing it to regain 1 SP in your Primal Wellspring pool.

Ancient Awakening
The mightiest of geomancers, it is said, see echoes of an ancient world - fierce and primordial, where primals reigned and the elements were yet untamed. And by their power, such a world can live again. Beginning at 18th level, whenever you use your Geomancy ability, you can choose one of the following benefits.
 * Double the number of 10' squares covered by the ability.
 * Manifest a primordial version of a terrain effect, inflicting Disadvantage on any saving throws against its effects.
 * Manifest an ancient nexus effect, creating terrain with the qualities of two separate terrain effects you have prepared. Both apply to the affected area in full.