Crimson Titanopede

Obsidian Skin (4/Day). Once per round, the Crimson Titanopede can choose to neglect 31(4d12 + 6) damage from an attack.

Tunneling. The Crimson Titanopede can burrowing up to a depth of 30-feet, without any disadvantages.

Multi-attack. Once per turn, the Crimson Titanopede can make one Slam attack and two Bite attacks.

Slam. Melee Weapon Attack: +3 to hit, reach 20 ft., 1 target. Hit: 13 (3d6 + 4) bludgeoning damage.

Bite. Melee Weapon Attack: +4 to hit, reach 10 ft., 1 target. Hit: 8 (2d6 + 4) piercing damage.

Kindle. Once per turn, the Crimson Titanopede can recover all Legendary Actions. If it does this, it cannot attack this turn. Whilst using this action, any creatures within a 10-foot radius must roll a DC 15 Constitution saving throw, taking 1d12 fire damage on a fail, or half as much on a successful save.

The Crimson Titanopede can has 5 Legendary Action points which allow it to make one legendary action at any point during a round. Once it uses a legendary action, its corresponding points are expended. The Crimson Titanopede recovers all points during a short rest, or whenever it makes the Kindle action.

Volcanic Tremor (Costs 3 Actions). The Crimson Titanopede cause a minor earthquake, which spreads in a 60-foot radius. Any creatures within the 60-foot radius must roll a DC 17 Dexterity saving throw, taking 4d8 force damage on a fail, or half as much on a successful save. Any creatures which fail this save fall prone. Any creatures within a 15-foot radius must also roll a DC 18 Constitution saving throw, taking 3d12 fire damage on a fail, or half as much on a successful save.

Magma Breath (Costs 2 Actions). The Crimson Titanopede spits out a jet of lava in a 120-foot line. Any creatures in this line must roll a DC 18 Dexterity saving throw, taking 10d6 fire damage on a fail, or half as much on a successful save.