The rules as written are ambiguous - and so it's up to the DM's ruling (and designer clarification has gone both ways)
Unfortunately, it's not clear exactly how these rules interact. The troll has an ability which apparently specifies the only circumstances in which a troll dies, and these spells can cause creatures to die instantly; both are exceptions to ...
Have a non-slash damage type weapon.
Well, that's an easy one. I would usually have at least a simple bludgeoning weapon as a replacement - it might be usefull to bash skeletons as well! A warhammer or maul suits this problem nicely.
If you don't, improvise it!
As other answer mentioned, you can use your actual weapon as an improvised weapon. Instead ...
This does not work.
Your quote is outdated.
The Monster Manual Errata shows that you no longer should reference weapons. Meaning it doesn't matter what you attack with so long as that attack, not weapon, meets the criteria in the entry.
In this case you can make an attack with your unarmed strike that doesn't count as a weapon, but the fact that it is not ...
Based on the wording used for the Rakshasa's Limited Magic Immunity and the Helmed Horror's Spell Immunity, it fits the template text of the rules to just write a feature that explicitly states the custom immunity. In other words, we don't need a fancy template, because the stat block designers already just make up whatever they need for a particular ...
The spell doesn’t give objects a save — it just deals the damage directly. Only the paragraph about how it affects creatures gives a save.
This circumvents the object immunity rule, since it’s not being affected by an effect with a save, it’s just being dealt damage.
Yes, It Hits Your Character
Per page 194 of the PH (bold added for emphasis):
When you make an attack, your attack roll determines whether the attack hits or misses. To make an attack roll, roll a d20 and add the appropriate modifiers. lf the total of the roll plus modifiers equals or exceeds the target's Armor Class (AC),the attack hits.
Regardless of ...
Divine smite only requires you to hit, which immunity does not prevent
Some creatures have vulnerability, resistance, or immunity to certain types of damage. Particular creatures are even resistant or immune to damage from non-magical attacks [...]
Being immune means you are immune to damage from that particular damage type/attack. It doesn't make you ...
It allows for some explosive combat options and methods to gain extreme immunities
For example, a Tiefling gains resistance to fire damage, they could walk into a group of enemies and cast fireball on the ground and then use absorb elements to gain immunity to the damage of the spell and also all fire damage until the start of their next turn.
There are ...
Gary Gygax (2007): Elves' positive energy makes them immune to paralysis from ghouls
Gary Gygax answered exactly this question on a forum in 2007, (typo original):
When I devised the ghoul for the D&D game it was most assuredly with non-living energization, that is undead status, that enabled these creatures to exist and hunger for the flesh of dead ...
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 ...
If the total of the [attack] roll plus modifiers equals or exceeds the target's Armor Class (AC), the attack hits. (PHB p.194, emphasis mine)
That's all you need to hit: nothing mentioned about damage.
The (excellent) question was raised: is it possible that immunity actually prevents the hit? Looking for a definition, today I learned that none of ...
There's always going to be some clever exception if you try to phrase it negatively like that. This is D&D, not a limited computer program. If you want something fancier than "immune to everything but magic missile", you could say:
Regeneration. The chicken regains 1 hit point at the start of its turn. If the chicken takes damage from the magic ...
Immunity to a damage type does not, generally, confer immunity beyond that damage.
In the example of Chill Touch there are three effects: damage, preventing HP gain, and clinging. A resistance to necrotic damage does not prevent either of the other two effects; the second and third are each predicated on the hit, not upon the damage.
Compare this with the ...
A Rakshasa's Limited Immunity does not grant them immunity from the 5th level spell Animated Objects, but it is immune to the damage given by those Animated Objects, for a different reason (non-magical damage immunity).
Limited Magic Immunity does not apply to Animated Objects because the spell itself is not dealing the damage - it is done by the constructs ...
The spell is more specific, so the troll dies
The troll's regeneration ability is a specific rule that overrides the general rule, which is that monsters die immediately upon dropping to 0 HP. It's telling you that simply dropping the troll to 0 HP does not kill it, and dealing damage to the troll while it is at 0 HP also does not kill it (since the troll ...
Yes, it does
There are no caveats in the rules for casting a spell that ends up not affecting a creature. The rules on spell slots just state that when a character casts a spell, he or she expends a slot of that spell's level or higher...
After all, you simply don't know whether a spell will affect a creature or not until you try (like trying to fireball a ...
No, because the Creature has been sent by a third party entity, not the spell.
The Rakshasa itself is not being affected by the spell, but is a result of the spell.
You beseech an otherworldly entity for aid... That entity sends a celestial, an elemental, or a fiend loyal to it to aid you, making the creature appear in an unoccupied space within range.
I've seen three (4, now that I've seen harlandski's Gygax quote) reasons for Elves being immune to a Ghoul's paralysis ability:
Per the Gygax quote, elves are suffused with positive energy, rendering them immune to the negative energy which powers a Ghoul's paralysis.
Tolkien Immortality (and historical inertia)
Apparently, an old source ...
Upcasting does indeed bypass limited magic immunity
When a spellcaster casts a spell using a slot that is of a higher level than the spell, the spell assumes the higher level for that casting. (PHB p.201)
The general rule is that a spell cast using a higher level spell slot is actually that level spell for that casting for all relevant effects. There is ...
Yes, Demon Lords
In the recently released Mordenkainen's Tome of Foes, there are several extremely powerful enemies. Amongst them are the Demon Lords, creatures of near-deity level power. An example of this is the Demogorgon found on page 144. Amongst their damage immunities, demon lords have the following immunity (bold added):
bludgeoning, piercing, ...
I asked Chris Perkins this question, and his response was:
A werewolf needs magic, a magic weapon, or a silvered weapon to harm another werewolf. 
While he generally refers rules questions to Jeremy Crawford, this makes sense in relation to Curse of Strahd and why this particular werewolf would want the PC's assistance.
The Werewolf would still die
Werewolves aren't immune to all non-magical attacks, they are immune to "slashing, piercing, and bludgeoning damage from non-magical attacks" (emphasis mine).
Being burned at the stake would deal fire damage, and fire is still quite effective. Suffocation does not rely on dealing HP damage to kill in the first place.
Immunity to Frightened condition prevails
The mace doesn't say anything about ignoring condition immunities, so it doesn't. Any undead that is immune to the condition is not affected by the mace in this way.
Sneak attack damage is magical if the weapon used is magical.
The Sneak Attack feature says that the rogue adds extra damage to the weapon attack.
Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon.
This implies that the extra ...
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 ...
Any creature with Hover and a fly speed cannot fall by normal means and is therefore not susceptible to fall damage.
If a flying creature is knocked prone, has its speed reduced to 0, or is otherwise deprived of the ability to move, the creature falls, unless it has the ability to hover or it is being held aloft by magic, such as by the ...
Resistance/Immunity would apply (because the rule used in the question is defunct)
It's debatable whether or not sneak attack's damage is from the weapon: but one thing I can be sure of is that sneak attack damage is from the attack. This can be seen in the PHB (p. 196, bold added), where it states:
When you score a critical hit, you get to roll extra ...
Counterspell says that:
You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 3rd level or lower, its spell fails and has no effect. If it is casting a spell of 4th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a success, the creature'...
There is no disease condition or damage type in D&D 5e as noted here in this Stack Exchange question. Hence no corresponding immunities, etc.
A case could be made that if a monster is immune to poison they are also immune to disease as two mechanics are similar when listed as an attack or effect. But in the RAW text no monsters and very few other things ...
Yes, it's immune.
But only because Charnel Touch says so; not due to necromancy nor any of the other construct immunities.
Charnel Touch (Su): [...] At will, but no more than once per round, she can make a melee touch attack against a living foe that deals 1d8 points of damage, +1 per four class levels. This touch heals undead creatures, restoring 1 hit ...