Adamantine is a type of ferrous metal so it will be affected by Monster features which corrode and rust, including the Rust Monster's Antennae feature
The "Adamantine Weapons" section of Xanathar's Guide to Everything (page 78) states:
Adamantine is an ultrahard metal found in meteorites and extraordinary mineral veins. In addition to being used to craft ...
The lore given in the Monster Manual provides an answer
The stat block of any monster is not given in isolation, the Source Book (in this case the Monster Manual) provides lore of each monster presented, and there is no fluff text in 5e (it's rules text all the way down).
Creature of Ritual. [...] The overwhelming terror that foreshadows a mummy’s ...
Xanathar's Guide to Everything has guidelines for simultaneous effects; the person whose turn it is determines the order of simultaneous events
The meteor swarm spell states:
[...] A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one [...]
It gives no indication of these happening at ...
Power derived from souls is required
The Fiendish Codex 2 from 3.5e includes a lot of information regarding promotions, including on page 11:
Second, promoting a devil from one form to another requires a considerable expenditure of the divine magic harvested from the breakdown of corrupt souls.
Further, it is also mentioned on page 12 that this also ...
A surprised monster who rolls a 20+ on initiative can use lair actions because they are able to take actions, and their turn has passed
As you've quoted, the rules on lair actions state:
On initiative count 20 (losing all initiative ties), it can use one of its lair action options. It can’t do so while incapacitated or otherwise unable to take actions. ...
The conditions are linked so the Barbarian would be neither paralyzed nor frightened
The Dreadful Glare feature simply states:
[...] If the target fails the saving throw by 5 or more, it is also
paralyzed for the same duration [...]
emphasis is mine.
You can't also be paralyzed if you are not frightened in the first place.
Even if you were ...
Temp HP can't save the troll (or anyone else) from the consequences of having 0 hit points.
The rules are clear that temporary hit points aren't "real":
Temporary hit points aren't actual hit points; they are a buffer against damage, a pool of hit points that protect you from injury.
If you have 0 hit points, receiving temporary hit ...
Not all monster abilities need to be directly combat-related
First, you assume that the characters would know the details of the infection. They would likely realise they are infected by something, but the gradual reveal of its nature can be played for a certain amount of horror.
And just because Lesser Restoration is a relatively low-level spell (compared ...
The Change Shape feature does not work in this way
The Couatl's Change Shape feature states:
The couatl magically polymorphs into a humanoid or beast that has a challenge rating equal to or less than its own, or back into its true form [...]
The Couatl thus cannot turn into a variant human because that is a Player Character race option, and thus does ...
Any effect that removes the Restrained condition would suffice.
The ability you quoted states:
The Restrained target must repeat the saving throw at the end of its next turn. On a success, the effect ends on the target. On a failure, the target is Petrified until freed by the Greater Restoration spell or other magic.
If the Restrained condition is ...
Adamantine is a ferrous metal, at least for the purposes of a rust monster. From the rust monster's description(MM, 343):
Underground Scavengers. Rust monsters roam subterranean passages in search of ferrous metals such as iron, steel, adamantine, and mithral to consume.
So a Rust Monster's Iron Scent will detect adamantine items of any kind, their Rust ...
It is possible for celestials, even the most powerful ones, to be tricked by evil deities. They might become pawns, initially unaware that they are being played with. They might eventually get corrupted and fall. A famous example is Malkizid, a solar who was seduced into betraying Corellon by Lolth, and was later cast into the Nine Hells. Another example (...
Sending contacts the ID
This is going to be one of those answers where I try to prove a negative.
Reviewing the Intellect Devourer's Body Thief (BT) skill in detail, I noticed that at no point does the ability describe the victim as being dead until the end:
If the host body drops to 0 hit points, the intellect devourer must leave it. [...] The body ...
Bob doesn't need to roll the save, due to the immunity to being frightened.
Horrifying Visage states:
Each non-undead creature within 60 feet of the ghost that can see it
must succeed on a DC 13 Wisdom saving throw or be frightened for
1 minute. If the save fails by 5 or more, the target also ages 1d4 ×
10 years. A frightened target can repeat ...
One ability will work, the other won't
Although the ability is called "Rust Metal", the text indicates that the weapon corrodes rather than rusts. The exception being magical weapons, but adamatine weapons are not magical. Xanathar's Guide is the only place they are mentioned and this is what it says about them:
Adamantine is an ultrahard metal found in ...
There is no saving throw roll that could be missed by 5
In D&D 5e you only roll the dice when the outcome is in doubt. The Barbarian in this rage state cannot be frightened (effectively, immune), therefore no saving throw against the frightened condition is rolled, and consequently there is nothing to check to see if it misses by 5 or more. As ...
RAW, the reach of an unarmed strike should be 5 feet unless otherwise noted.
From the 5e Player's Handbook, page 195:
Most creatures have a 5-foot reach and can thus attack targets within 5 feet of them when making a melee attack. Certain creatures (typically those larger than Medium) have melee attacks with a greater reach than 5 feet, as noted in their ...
Strict RAW reading – perhaps Wish
The ability only describes how to get rid of it after the second fail, so there are no obvious options. Moreover, Greater Restoration only removes petrified condition:
One effect that charmed or petrified the target
(and some others, but not restrained and not the first stage of Gorgon's Petrifying Breath) but the ...
The stat block for the Elder Oblex (MToF, p. 219) already states what happens when it uses its Eat Memories ability:
When an oblex causes a target to become memory drained, the oblex learns all the languages the target knows and gains all its proficiencies, except any saving throw proficiencies.
It doesn't state that it learns the spells known or ...
Apply them simultaneously
The spell does 20d6 bludgeoning damage and 20d6 fire regain - roll both sets of dice and take the fire from the bludgeoning. If its positive they suffer that much damage, if its negative they regain that many hit points (up to their maximum), if its exactly equal then nothing happens.
The devil can use each chain to make an additional chain attack. "Chain attack" simply refers to the attack the devil can already make that's titled "Chain", which you've quoted, and includes both the grapple and the restraining effect.
"An animated chain can grapple one creature of its own" should be read as saying that, for purposes of the "if the ...
They very likely have one; it would be up to the GM how this item works
The Night Hag's entry in the monster manual states:
[...] Night Hag Items. A night hag carries two very rare magic items that she must craft for herself. If either object is lost, the night hag will go to great lengths to retrieve it, as creating a new tool takes time and effort.
The rule states:
You can make an opportunity attack when a hostile creature that you can see moves out of your reach.
The Giant reach is unknown (see the related question), but the one and only melee attack from the stats block has 15 ft reach. If we assume its reach is 15 ft, and you are moving just 5 ft away from it, you are not "out of its reach".
Yes, it is innate to the Death Knight
This question has been covered previously here. The extra damage is innate to the Death Knight rather than the sword. Other monsters like the Erinyes have similar effects.
If you cast the true polymorph spell prior to the battle, and allow one hour to pass to make it "permanent", you can then draw upon the ...
"You" in the context of the Monster Manual is meant to refer to whomever the DM is.
This bestiary is for storytellers and worldbuilders. If you have ever thought about running a Dungeons & Dragons game for your friends, either a single night's adventure or a long-running campaign, this tome contains page after page of inspiration. It's your one-stop ...
The Slaadi incubation effect isn't a combat ability, it's how they reproduce
Combat challenge is determined by how much damage a monster can deal out over 3 rounds, and how hard they are for a party to take down (AC, HP etc). This ability does neither of these things and thus is not a combat challenge and doesn't impact CR.
Abilities like this, that don't ...
Orcus can choose what kind of undead he summons.
The Wand of Orcus is an artifact that is fully detailed on DMG p. 227. The description of its Call Undead ability says:
While you are holding the wand, you can use an action to conjure skeletons and zombies, calling forth as many of them as you can divide 500 hit points among, each undead having average ...
If the kraken wants to bite a creature grappled by its tentacle then eithier it needs to move its mouth to the creature, which it can do through moving, or move the creature to its mouth, which it can also do through moving as follows:
Moving a Grappled Creature: When you move, you can drag or carry the Grappled creature with you, but your speed is ...
Bob the Brave does not age
We can come to this conclusion directly if we examine what a Wisdom saving throw is meant to represent. The Dungeon Master's Guide Saving Throws subsection, of the Using Ability Scores section, provides us with some key information.
A Wisdom saving throw is used for:
Resisting effects that charm, frighten, or otherwise ...
Based on the wording of his ability, Orcus conjures undead creatures of his choice.
Acererak (Tomb of Annihilation) is a creature, he is undead, and he has under 500 average HP. He is a valid target for the spell. I'd use discretion conjuring a named lich since they are very powerful compared to your run of the mill undead.
Because this ability states ...