Necrotech Thunderer

Family: Necrotech

Huge undead, neutral evil

Armor Class 14 (natural armor)
Hit Points 126 (11d12 + 55)
Speed 20 ft.

20 (+5) 5 (–3) 21 (+5) 5 (–3) 14 (+2) 9 (–1)

Saving Throws Dex +0, Wis +5
Skills Perception +5
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities necrotic, poison
Condition Immunities blinded, poisoned
Senses blindsight 120 ft., passive Perception 15
Languages understands Common and Darakhul but can’t speak
Challenge 8 (3,900 XP)
Proficiency Bonus +3


  • Siege Monster. The necrotech thunderer deals double damage to objects and structures.
  • Turn Resistance. The necrotech thunderer has advantage on saving throws against any effect that turns undead.
  • Undead Nature. The necrotech thunderer doesn’t require air, food, drink, or sleep.


  • Multiattack. The necrotech thunderer makes two Trample attacks.
  • Trample. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 21 (3d10 + 5) bludgeoning damage.
  • Ballista Shot. The necrotech thunderer chooses up to two points it can see within 120 feet of it. The thunderer can’t choose a point within 10 feet of it. Each creature within 5 feet of a point must make a DC 15 Constitution saving throw, taking 14 (4d6) necrotic damage on a failed save, and half as much damage on a successful one. If a creature is within 5 feet of both points, it has disadvantage on the saving throw, but it takes damage from only one effect, not both.
  • Concentrated Shot (Recharge 5–6). The necrotech thunderer picks a point it can see within 120 feet of it. Each creature within 20 feet of that point must make a DC 15 Constitution saving throw. On a failure, a creature takes 35 (10d6) necrotic damage and suffers one level of exhaustion. On a success, a creature takes half the damage and doesn’t suffer a level of exhaustion.


The undead elephant has had the top of its skull and spine carved out, replaced with an enormous ballista of polished brass.

Swirling purple energy condenses atop the ballista, forming the core of a terrible magical projectile.

Necrotech thunderers are dedicated undead siege weapons. Their bodies are built from elephants, triceratops, or similarly massive quadrupeds, while their skulls and spines are carved open to make room for ballistae carved from slain treants.

A thunderer’s body is then hardened against necrotic energy, allowing it to channel explosive bolts of necromantic magic through the siege weapon built into its spine.

Dedicated Artillery. Thunderers are expensive and poor at defending themselves in melee. As a result, they are deployed with sizable bodyguards capable of holding back the enemy.

Thunderers are often priority targets for elite teams working against undead armies, because their necromantic ballistae can quickly reduce formations of lesser troops to rotting flesh or rip jagged holes in fortifications.

Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

This is not the complete section 15 entry - see the full license for this page