Brontosaurus

Gargantuan beast (dinosaur), Unaligned

Armor Class 15 (natural armor)

Hit Points 121 (9d20 + 27)

Speed 30 ft.

STR 21 (+5)

DEX 9 (-1)

CON 17 (+3)

INT 2 (-4)

WIS 10 (+0)

CHA 7 (-2)

Saving Throws CON +6

Senses passive Perception 10

Languages —

Challenge 5

Actions

Stomp. Melee Weapon Attack: +8 to hit, reach 20 ft., one target. Hit: 27 (5d8 + 5) bludgeoning damage, and the target must succeed on a DC 14 Strength saving throw or be knocked prone.

Tail. Melee Weapon Attack: +8 to hit, reach 20 ft., one target. Hit: 32 (6d8 + 5) bludgeoning damage.

Source

Mordenkainen Presents: Monsters of the Multiverse, p. 95