Medium monstrosity, lawful evil

Armor Class 15 (natural armor)
Hit Points 127 (17d8 + 51)
Speed 30 ft.

STR	DEX	CON	INT	WIS	CHA
10 (+0)	15 (+2)	16 (+3)	12 (+1)	13 (+1)	15 (+2)

Saving Throws 
Skills Deception +5, Insight +4, Perception +4, Stealth +5
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses darkvision 60 ft., passive Perception 14
Languages Common
Challenge 6 (2300 XP)

Petrifying Gaze. When a creature that can see the medusa’s eyes starts its turn within 30 feet of the medusa, the medusa can force it to make a DC 14 Constitution saving throw if the medusa isn’t incapacitated and can see the creature. If the saving throw fails by 5 or more, the creature is instantly petrified. Otherwise, a creature that fails the save begins to turn to stone and is restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success. The petrification lasts until the creature is freed by the ““ spell or other magic. Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can’t see the medusa until the start of its next turn, when it can avert its eyes again. If the creature looks at the medusa in the meantime, it must immediately make the save. If the medusa sees itself reflected on a polished surface within 30 feet of it and in an area of bright light, the medusa is, due to its curse, affected by its own gaze.

Actions

Multiattack. The medusa makes either three melee attacks—one with its snake hair and two with its shortsword—or two ranged attacks with its longbow.

Snake Hair. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 2) piercing damage plus 14 (4d6) poison damage.

Shortsword. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage.

Longbow. Ranged Weapon Attack: +5 to hit, range 150/600 ft., one target. Hit: 6 (1d8 + 2) piercing damage plus 7 (2d6) poison damage.

Large monstrosity, chaotic evil

Armor Class 13 (natural armor)
Hit Points 45 (6d10 + 12)
Speed 10 ft., swim 40 ft.

STR	DEX	CON	INT	WIS	CHA
18 (+4)	10 (+0)	15 (+2)	8 (-1)	10 (+0)	9 (-1)

Saving Throws 
Skills 
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses darkvision 60 ft., passive Perception 10
Languages Abyssal, Aquan
Challenge 2 (450 XP)

Amphibious. The merrow can breathe air and water.

Actions

Multiattack. The merrow makes two attacks: one with its bite and one with its claws or harpoon.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage.

Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (2d4 + 4) slashing damage.

Harpoon. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 11 (2d6 + 3) piercing damage. If the target is a Huge or smaller creature, it must succeed on a Strength contest against the merrow or be pulled up to 20 feet toward the merrow.

Large monstrosity, unaligned

Armor Class 13 (natural armor)
Hit Points 59 (7d10 + 21)
Speed 40 ft.

STR	DEX	CON	INT	WIS	CHA
20 (+5)	12 (+1)	17 (+3)	3 (-4)	12 (+1)	7 (-2)

Saving Throws
Skills Perception +3
Damage Resistances
Damage Immunities
Condition Immunities
Senses darkvision 60 ft., passive Perception 13
Languages --
Challenge 3 (700 XP)

Keen Sight and Smell. The owlbear has advantage on Wisdom (Perception) checks that rely on sight or smell.

Actions

Multiattack. The owlbear makes two attacks: one with its beak and one with its claws.

Beak. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 10 (1d10 + 5) piercing damage.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) slashing damage.

Large monstrosity, unaligned

Armor Class 13 (natural armor)
Hit Points 32 (5d10 + 5)
Speed 30 ft., climb 30 ft.

STR	DEX	CON	INT	WIS	CHA
15 (+2)	15 (+2)	12 (+1)	6 (-2)	10 (+0)	6 (-2)

Saving Throws 
Skills Stealth +6
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses darkvision 60 ft., passive Perception 10
Languages --
Challenge 3 (700 XP)

Ethereal Jaunt. As a bonus action, the spider can magically shift from the Material Plane to the Ethereal Plane, or vice versa.

Spider Climb. The spider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Walker. The spider ignores movement restrictions caused by webbing.

Actions

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 18 (4d8) poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way. A phase spider possesses the magical ability to phase in and out of the Ethereal Plane. It seems to appear out of nowhere and quickly vanishes after attacking. Its movement on the Ethereal Plane before coming back to the Material Plane makes it seem like it can teleport.

Gargantuan monstrosity, unaligned

Armor Class 18 (natural armor)
Hit Points 247 (15d20 + 90)
Speed 50 ft., burrow 30 ft.

STR	DEX	CON	INT	WIS	CHA
28 (+9)	7 (-2)	22 (+6)	1 (-5)	8 (-1)	4 (-3)

Saving Throws Con +11, Wis +4
Skills 
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses blindsight 30 ft., tremorsense 60 ft., passive Perception 9
Languages --
Challenge 15 (13000 XP)

Tunneler

. The worm can burrow through solid rock at half its burrow speed and leaves a 10-foot-diameter tunnel in its wake.

Actions

Multiattack. The worm makes two attacks: one with its bite and one with its stinger.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 22 (3d8 + 9) piercing damage. If the target is a Large or smaller creature, it must succeed on a DC 19 Dexterity saving throw or be swallowed by the worm. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the worm, and it takes 21 (6d6) acid damage at the start of each of the worm’s turns. If the worm takes 30 damage or more on a single turn from a creature inside it, the worm must succeed on a DC 21 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the worm. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 20 feet of movement, exiting prone.

Tail Stinger. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 19 (3d6 + 9) piercing damage, and the target must make a DC 19 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.

Huge monstrosity, unaligned

Armor Class 17 (natural armor)
Hit Points 195 (17d12 + 85)
Speed 30 ft., burrow 20 ft.

STR	DEX	CON	INT	WIS	CHA
24 (+7)	13 (+1)	21 (+5)	4 (-3)	10 (+0)	5 (-3)

Saving Throws 
Skills 
Damage Resistances 
Damage Immunities cold, fire
Condition Immunities 
Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 10
Languages --
Challenge 11 (7200 XP)

Heated Body. A creature that touches the remorhaz or hits it with a melee attack while within 5 feet of it takes 10 (3d6) fire damage.

Actions

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 40 (6d10 + 7) piercing damage plus 10 (3d6) fire damage. If the target is a creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the remorhaz can’t bite another target.

Swallow. The remorhaz makes one bite attack against a Medium or smaller creature it is grappling. If the attack hits, that creature takes the bite’s damage and is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the remorhaz, and it takes 21 (6d6) acid damage at the start of each of the remorhaz’s turns. If the remorhaz takes 30 damage or more on a single turn from a creature inside it, the remorhaz must succeed on a DC 15 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the remorhaz. If the remorhaz dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 15 feet of movement, exiting prone.

Large monstrosity, neutral evil

Armor Class 20 (natural armor)
Hit Points 93 (11d10 + 33)
Speed 10 ft., climb 10 ft.

STR	DEX	CON	INT	WIS	CHA
18 (+4)	8 (-1)	17 (+3)	7 (-2)	16 (+3)	6 (-2)

Saving Throws 
Skills Perception +6, Stealth +5
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses darkvision 60 ft., passive Perception 16
Languages --
Challenge 5 (1800 XP)

False Appearance. While the roper remains motionless, it is indistinguishable from a normal cave formation, such as a stalagmite.

Grasping Tendrils. The roper can have up to six tendrils at a time. Each tendril can be attacked (AC 20; 10 hit points; immunity to poison and psychic damage). Destroying a tendril deals no damage to the roper, which can extrude a replacement tendril on its next turn. A tendril can also be broken if a creature takes an action and succeeds on a DC 15 Strength check against it.

Spider Climb. The roper can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Multiattack. The roper makes four attacks with its tendrils, uses Reel, and makes one attack with its bite.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 22 (4d8 + 4) piercing damage.

Tendril. Melee Weapon Attack: +7 to hit, reach 50 ft., one creature. Hit: The target is grappled (escape DC 15). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the roper can’t use the same tendril on another target.

Reel. The roper pulls each creature grappled by it up to 25 feet straight toward it.

Gargantuan monstrosity, unaligned

Armor Class 15 (natural armor)
Hit Points 248 (16d20 + 80)
Speed 20 ft., fly 120 ft.

STR	DEX	CON	INT	WIS	CHA
28 (+9)	10 (+0)	20 (+5)	3 (-4)	10 (+0)	9 (-1)

Saving Throws Dex +4, Con +9, Wis +4, Cha +3
Skills Perception +4
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses passive Perception 14
Languages --
Challenge 11 (7200 XP)

Keen Sight. The roc has advantage on Wisdom (Perception) checks that rely on sight.

Actions

Multiattack. The roc makes two attacks: one with its beak and one with its talons.

Beak. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 27 (4d8 + 9) piercing damage.

Talons. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 23 (4d6 + 9) slashing damage, and the target is grappled (escape DC 19). Until this grapple ends, the target is restrained, and the roc can’t use its talons on another target.

Medium monstrosity, unaligned

Armor Class 14 (natural armor)
Hit Points 27 (5d8 + 5)
Speed 40 ft.

STR	DEX	CON	INT	WIS	CHA
13 (+1)	12 (+1)	13 (+1)	2 (-4)	13 (+1)	6 (-2)

Saving Throws 
Skills 
Damage Resistances 
Damage Immunities 
Condition Immunities 
Senses darkvision 60 ft., passive Perception 11
Languages --
Challenge 44928 (100 XP)

Iron Scent. The rust monster can pinpoint, by scent, the location of ferrous metal within 30 feet of it.

Rust Metal. Any nonmagical weapon made of metal that hits the rust monster corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed. Nonmagical ammunition made of metal that hits the rust monster is destroyed after dealing damage.

Actions

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 5 (1d8 + 1) piercing damage.

Antennae. The rust monster corrodes a nonmagical ferrous metal object it can see within 5 feet of it. If the object isn’t being worn or carried, the touch destroys a 1-foot cube of it. If the object is being worn or carried by a creature, the creature can make a DC 11 Dexterity saving throw to avoid the rust monster’s touch. If the object touched is either metal armor or a metal shield being worn or carried, its takes a permanent and cumulative −1 penalty to the AC it offers. Armor reduced to an AC of 10 or a shield that drops to a +0 bonus is destroyed. If the object touched is a held metal weapon, it rusts as described in the Rust Metal trait.

Gargantuan monstrosity, unaligned

Armor Class 25 (natural armor)
Hit Points 676 (33d20 + 330)
Speed 40ft

STR	DEX	CON	INT	WIS	CHA
30 (+10)	11 (+0)	30 (+10)	3 (-4)	11 (+0)	11 (+0)

Saving Throws Int +5, Wis +9, Cha +9
Skills 
Damage Resistances 
Damage Immunities fire, poison; bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunities charmed, frightened, paralyzed, poisoned
Senses blindsight 120ft., passive Perception 10
Languages -
Challenge 30 (155000 XP)

Legendary Resistance (3/Day). If the tarrasque fails a saving throw, it can choose to succeed instead.

Magic Resistance. The tarrasque has advantage on saving throws against spells and other magical effects.

Reflective Carapace. Any time the tarrasque is targeted by a ““ spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, the tarrasque is unaffected. On a 6, the tarrasque is unaffected, and the effect is reflected back at the caster as though it originated from the tarrasque, turning the caster into the target.

Siege Monster. The tarrasque deals double damage to objects and structures.

Actions

Multiattack. The tarrasque can use its Frightful Presence. It then makes five attacks: one with its bite, two with its claws, one with its horns, and one with its tail. It can use its Swallow instead of its bite.

Bite. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 36 (4d12 + 10) piercing damage. If the target is a creature, it is grappled (escape DC 20). Until this grapple ends, the target is restrained, and the tarrasque can’t bite another target.

Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 28 (4d8 + 10) slashing damage.

Horns. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 32 (4d10 + 10) piercing damage.

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 24 (4d6 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be knocked prone.

Frightful Presence. Each creature of the tarrasque’s choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the tarrasque is within line of sight, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the tarrasque’s Frightful Presence for the next 24 hours.

Swallow. The tarrasque makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite’s damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the tarrasque, and it takes 56 (16d6) acid damage at the start of each of the tarrasque’s turns. If the tarrasque takes 60 damage or more on a single turn from a creature inside it, the tarrasque must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the tarrasque. If the tarrasque dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

Legendary Actions

The tarrasque can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The tarrasque regains spent legendary actions at the start of its turn.

Attack. The tarrasque makes one claw attack or tail attack.

Move. The tarrasque moves up to half its speed.

Chomp (Costs 2 Actions). The tarrasque makes one bite attack or uses its Swallow.