Obsidian Shale Beast

Family: Shale

Medium elemental, unaligned

Armor Class 18 (natural armor), 20 with Obsidian Armor
Hit Points 161 (19d8 + 76)
Speed 40 ft., burrow 30 ft.

STR	DEX	CON	INT	WIS	CHA
19 (+4)	20 (+5)	19 (+4)	3 (-4)	18 (+4)	9 (-1)

Saving Throws Con +8, Wis +8
Skills Stealth +9
Damage Vulnerabilities thunder
Damage Resistances fire
Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 14
Languages –
Challenge 10 (5,900 XP)
Proficiency Bonus +4

SPECIAL TRAITS

• Obsidian Armor. The beast’s hide is made of brittle obsidian, giving it an AC of 20. Once the beast is reduced to less than half its hit points, or immediately upon being damaged by a critical hit, its obsidian armor breaks, reducing its AC to 18. While the armor is unbroken, any creature that touches the beast, hits it with an unarmed attack, tries to grapple it, or starts its turn grappling or grappled by the beast takes 10 (3d6) slashing damage. A creature can take this damage only once per turn.
• Rock Stride. The beast ignores difficult terrain in caves and rocky areas.
• Stone Camouflage. The beast has advantage on Dexterity (Stealth) checks made to hide in rocky terrain.

ACTIONS

• Multiattack. The beast makes two obsidian claw attacks or two obsidian shard attacks.
• Obsidian Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) slashing damage.
• Obsidian Shard. Ranged Weapon Attack: +9 to hit, range 90/180 ft., one target. Hit: 14 (2d8 + 5) slashing damage.
• Song of the Earth (Recharge 6). The beast rubs the sharp edge of one of its legs against its own hide, creating a subsonic hum that both soothes and stimulates other shale spitters. Each shale spitter within 120 feet of the beast has advantage on saving throws and can make a melee attack as a bonus action until the end of its next turn.

ABOUT

At first glance, obsidian shale beasts look more like walking mounds of knives than living creatures. But these strange grasshopper-like beings do share the same lineage as common shale spitters; their stony exteriors have simply morphed from many years of consuming and digesting brittle, vitreous minerals and rocks such as quartz, calcite, and obsidian.

When encountered on their own, obsidian shale beasts are typically found much deeper underground than most shale spitters. They have a particular fondness for veins of molten rock, and are more prevalent in mountains with active volcanoes, where searing heat and incredible pressure hone their bodies into jagged weapons. Old obsidian shale beasts who have spent decades or even centuries near lava flows or magma veins can grow to incredible sizes and develop brutally sharp, extra-dense carapaces.

Owing to their brittle and oblong bodies, obsidian shale beasts cannot curl up into protective balls like most shale spitters. Rather, obsidian shale beasts rely on their natural armor, which is as brittle and sharp as an obsidian blade, to protect them from inter-pack tussles, attacks from predators, and sudden cave-ins.

A shale spitter pack with an obsidian shale beast among their numbers is far more likely to survive times of crisis. When an unmatchable predator like a cavern troll or cave worm attacks the pack, it’s up to the obsidian shale beast to rally its kin to safety while fending off the intruder. The shale beast accomplishes this with its unique ability to produce a subsonic hum that snaps other shale spitters out of torpors and drives them to action. Shale beasts are also unusually noble, and will stay behind to distract an attacker if doing so will enable its pack mates to escape.