Brunnar, Duke of Gris Mawr

Earth Glide. Brunnar can burrow through nonmagical, unworked earth and stone. While doing so, the elemental does not disturb the material it moves through.

Siege Monster. Brunnar deals double damage to objects and structures.

Rocky Hide. Brunnar's rocky hide provides it with additional protection. It has resistance to nonmagical bludgeoning, piercing, and slashing damage.

Multiattack. Brunnar makes two attacks: one with its Slam and one with its Stonehewn Slam if it can.

Slam. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 24 (3d10+6 bludgeoning damage.

Stonehewn Slam (Recharge 5-6). Brunnar concentrates its elemental power into its slam attack, causing the ground to quake upon impact. Each creature in a 20-foot radius centered on the target must make a DC 16 Strength saving throw or be knocked prone and take 28 (4d10+6) bludgeoning damage. On a successful save, the creature takes half damage and isn't knocked prone.

Stone Toss. Ranged Weapon Attack: +6 to hit, range 60/240 ft., one target. Hit: 19 (3d8+6) bludgeoning damage. If the target is a creature, it must succeed on a DC 16 Strength saving throw or be knocked prone.

Rocky Eruption (Recharge 6). Brunnar causes the ground to erupt in a 20-foot radius centered on himself. Each creature in that area must make a DC 16 Dexterity saving throw, taking 45 (10d8) bludgeoning damage on a failed save, or half as much damage on a successful one. The area becomes difficult terrain until the end of Brunnar's next turn.

Earth Infusion. As a bonus action, Brunnar can channel his elemental essence, gaining temporary hit points equal to its current hit points (up to a maximum of 168). These temporary hit points last for 1 minute or until depleted.