Dinosaur, Diplodocus

Family: Dinosaurs

Gargantuan beast, unaligned

Armor Class 16 (natural armor)
Hit Points 198 (12d20 + 72)
Speed 30 ft.

21 (+5) 10 (+0) 23 (+6) 2 (-4) 14 (+2) 5 (-3)

Skills Athletics +9
Damage Resistances bludgeoning
Senses passive Perception 12
Challenge 10 (5,900 XP)


  • Trampling Charge. If the Diplodocus moves at least 20 feet straight toward a creature and then hits it with a tail attack on the same turn, that target must succeed on a DC 17 Strength saving throw or be knocked prone. If the target is prone, the Diplodocus can make one stomp attack against it as a bonus action.
  • Unstoppable. The Diplodocus has advantage on ability checks and saving throws against effects that would restrain it or knock it prone.


  • Multiattack. The Diplodocus makes two Tail Whip attacks.
  • Tail Whip. Melee Weapon Attack: +9 to hit, reach 20 ft., one target. Hit: 18 (3d8 + 5) slashing damage. If the target is a Large or smaller creature, it must succeed on a DC 17 Strength check or be knocked prone.
  • Stomp. Melee Weapon Attack: +9 to hit, reach 5 ft., one prone creature. Hit: 21 (3d10 + 5) bludgeoning damage.


The Diplodocus can take three legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The Diplodocus regains spent legendary actions at the start of its turn.

  • Move. The Diplodocus moves up to half its speed.
  • Stomp (costs 2 actions). The Diplodocus makes one stomp attack.
  • Whip Crack (costs 3 actions). The Diplodocus whips its tail in the air to create a thunderous crack. Each creature within 20 feet of it must succeed on a DC 17 Wisdom saving throw or take 14 (4d6) thunder damage and become frightened until the end of its next turn.


Grazers of lakes, bogs, and in some cases, the shallow seas, the stately Diplodocus is generally not a threat. Slow moving, confident in their bulk, they rarely do more than watch passing creatures. These massive beasts move in small family groups and gather during the mating season in great herds to lay their eggs in dry nests. It is during this migration and mating period that they are the most dangerous, for the normally placid creatures become ill-tempered until their young hatch and become large enough to accompany their parents back to the lakes and swamps.

Section 15: Copyright Notice

Tome of Horrors 2020, (C) 2020, Necromancer Games

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