Aspect of Muld

Earth Glide. The creature can burrow through nonmagical, unworked earth and stone. While doing so, it doesn't disturb the material it moves through.

Siege Monster. The creature deals double damage to objects and structures.

Guardian of Nature. Terrain within 15ft of the creature is considered difficult terrain for it's enemies.

Observant. The creature has a +5 to it's passive perception and passive investigation

Spellcasting. The creatures's innate spellcasting ability is Constitution (spell save DC 15). The creature can cast the following spells:

At will: Druidcraft, Mold Earth

1/day: Plant Growth, Stone Shape, Wall of Stone

Multiattack. The elemental makes two greatclub attacks.

Slam. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.

Thorn Whip. Melee Weapon Attack: +7 to hit, reach 30 ft., one target. Hit: 12 (3d6) piercing  damage and upon a hit pulls the target 10ft closer to the creature.

The creature can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The creature regains spent legendary actions at the start of its turn.

Detect. The creature makes a Wisdom (Perception) check.

Slam. The creature makes one slam attack.

Erupted Earth. (Costs 2 Actions). The creature chooses a point it can see on the ground within 120ft. A fountain of churned earth and stone erupts in a 20-foot cube centered on that point. Each creature in that area must make a Dexterity saving throw. A creature takes 3d12 bludgeoning damage and are knocked prone on a failed save, or half as much damage on a successful one and are not knocked prone.