Huge construct, unaligned
Armor Class 24 (natural armor)
Hit Points 478 (29d12 + 290)
Speed 20 ft.
Damage Resistances cold, lightning, acid
Damage Immunities fire, poison, psychic; bludgeoning, piercing, and slashing damage from nonagical attacks that aren't adamantine
Condition Immunities blinded, charmed, deafened exhaustion, frightened, paralyzed, petrified, poisoned, stunned
Senses darkvision 120 ft., passive Perception 10
Languages understands the languages of its creator but can’t speak
Challenge 29 (135,000 XP)
Immutable Form. The behemoth is immune to any spell or effect that would alter its form.
Limited Magic Immunity. The behemoth is immune to any spell of 6th level or lower.
Magic Resistance. The behemoth has advantage on saving throws against spells and other magical effects.
Magic Weapons. The behemoth's weapon attacks are magical.
Mass Shift. The behemoth has a limited ability to reshape its form to fit into a tight area. It does not take a penalty on attack rolls or to Armor Class when squeezing through a tight space.
Siege Monster. The behemoth deals double damage to objects and structures.
Stability. The behemoth has advantage on saving throws or abillity checks against being pushed or knocked prone.
Thunderous Steps. The ponderous steps of a slaughterstone behemoth shake the very earth. Any creature within 5 feet of the behemoth when it moves must succeed on a DC 24 Dexterity save or fall prone.
Trample. If the behemoth moves at least 10 feet straight toward a target and hits it with a slam attack on the same turn it must succeed a DC 24 Strength saving throw or be knocked prone. If the creature is prone, the behemoth can make a slam attack against it as a bonus action.
Multiattack. The behemoth makes four slam attacks.
Slam. Melee Weapon Attack: +19 to hit, reach 5 ft., one target. Hit: 57 (4d6 + 13) bludgeoning damage.
Unbridled Fury. In response to a melee attack, the behemoth can make one melee weapon attack with advantage against the attacker.
Only in legends have most heard of the hulking construct known as the slaughterstone behemoth. These massive monstrosities are spoken of in stories old as the rock they’re forged from; stories of entire armies ground to paste within a matter of minutes. Only one race, however, truly knows the nature and power of these artificial beasts; the dwarves.
Dwarven Engineering. The first slaughterstone behemoth is the product of combining dwarven engineering and powerful magic, and nearly all since then are as well. Those outside of dwarven realms, the few that exist, were commissioned by a powerful noble as a personal bodyguard.
But even among the dwarves, only the wealthiest and most powerful nobles have access to a behemoth and most can only afford one. These monstrosities are composed of a special type of mineral, aptly named slaughterstone as getting it is liable to kill you. It is only found deep in the underdark and so the dwarves have to venture far into danger to create even a single behemoth.
Of course, that was their initial intention; to hold back the horrors of the Underdark. For this reason, in addition to a golem’s quasi-intelligence, the slaughterstone behemoth comes with a limited ability to squeeze its form through tight spaces, via magically altering its shape. Only the tightest spaces are a hindrance, in which case the behemoth just smashes its way through.
Battlefield Beatdown. The slaughterstone behemoth is designed with only one purpose in mind: as an engine of war. Whether it be the hordes of the Underdark or the armies of the surface, dwarves built the behemoth to destroy whatever it faces.
Legends tell of whole armies, with at least forty platoons, turned to a thick covering of paste and carrion. Armor is left crushed and dented, weapons broken and bent, all beyond repair after facing the behemoth’s nigh-indestructible construction and powerful arsenal. Any normal soldier would be a fool to face such a beast, and even the most powerful of heroes should best to be cautious when against one.
That said, the slaughterstone behemoth is built with an inherent weakness: powerful magic. While a novice or even an apprentice would be like a fly to it, a more powerful spellcaster who can hit the behemoth from afar can severely damage the large construct. This is particularly effective, as a standard behemoth has no ranged attacks at all and is not built with maneuverability in mind. As such, a conclave of powerful wizards could tear through a behemoth enough to where, by the time it reaches them, a team of powerful melee compatriots could finish it off.
Constructed Nature. A slaughterstone behemoth doesn't require air, food, drink, or sleep.