Overview
The Primordial Crags is an epic level encounter facing off against an aspect of Earth. The Crags have been corrupted by an outside entity, the aspect of corruption. They're sending forces to the material plane to take what they want and enslave any citizens they can capture.
Fight Synopsis
There are a LOT of moving parts in this fight. One of the big decisions you'll have to make throughout is the balance of Earthen Form vs Medusa Form. Earthen Form makes them a bit more durable, but Medusa Form gives them an intense amount of maneuverability.
In addition, each of the Crags has a unique ability that is used at the end of their turns - utilize these abilities to assist in fight pacing. If players are getting overwhelmed, have Prima Tala temporarily stop bringing in Earth Elementals, or conversely bring in more if they're stomping. If one of the Crags is being hard targeted, utilize Prima Kata's Concealing Dust ability to raise their defenses. Finally, Prima Crios' ability to dictate where crystals are being thrown can lend to some fight changing moves. Interrupting a concentration or healing them at a key time should not be underestimated.
One big note as well - it's important to display that the three sisters have a shared pool. When one gets hit, describe the other three flinching due to this, or occasionally a beam of energy bouncing between the trio.
Personality
The Crags are ancient. They've been around for as long as time, and they know how to handle themselves. They're confident in their abilities, and will not fall for simple ploys. They will use the chaotic nature of their arena and their fight to their advantage, striking the foes that seem more threatening first when openings are created.
Prima Tala is the strongest of the three, and leads their forces. She does not care much for talking, and only cares for battle. When roleplaying her, you can have her be impatient, rearing to go at all times. She will often have her anger get the better of her, but will be calmed down by Prima Kata.
Prima Kata is the voice of the sisters, and looks the least monstrous. Those that have sighted her often refer to her as a beauty, right before she moves forward and tears them apart. She will try to disarm any opponents with her words, which have an almost alluring subtext to them. Failing that, she is also ruthless in battle. She is extremely even tempered, and is the "voice of reason" of the sisters.
Prima Crios is the brains of the sisters, and often plays almost a game of chess with her opponents. She is constantly thinking several moves ahead to head off any tricks that the enemy may have. She will typically stay near the back, acting almost as a spotter - calling out threats to her sisters and analyzing the scene to dictate where the best place to throw crystals would be.
Brief Lore
Not a whole lot is known about the Primordial Crags - they have largely kept to themselves within the Plane of Earth. From what has been deduced, they are the leaders of the plane. They all have various strengths, and they started invading the Material Plane to take the resources of the mortals. They had no desire to do this initially, but were twisted by the aspect of corruption - The Primordial Decay. Decay cannot happen if there is peace, and so the peace was broken. The Plane of Earth spilled into the Material Plane and now they must be stopped.
Music
The right music helps set the tone amazingly. For this encounter, a very primal intense track is important. Monstrous Might from Gwent: The Witcher Card Game should do the trick!