How long do the temporary HP gained from the Aberrant Dragonmark feat last?

The Aberrant Dragonmark feat states:

You learn that spell and can cast it through your mark. Once you cast it, you must finish a short or long rest before you can cast it again through the mark. Constitution is your spellcasting ability for these spells. When you cast the 1st-level spell through your mark, you can expend one of your Hit Dice and roll it. If you roll an even number, you gain a number of temporary hit points equal to the number rolled.

How long do those HP last?

Can the cantrips gained from the Dragonmark feat be cast multiple times?

The Dragonmark Feat from Unearthed Arcana: Eberron says:

You gain the ability to innately cast spells and cantrips, as summarized in the Dragonmark Benefits table, using the spellcasting ability listed under the Ability column. You cast each spell at its lowest level. Once you cast a given spell this way, you must finish a long rest before you can cast it innately again. You must still expend any material components.

Every dragonmark gives the character access to a first, second and third level spell, as well as a cantrip. The second and third level spells can only be cast if the character is of high enough level (, 5th and 9th, respectively).

Usually you can cast the cantrips you know infinitely often. But the way this feat is worded seems to imply, that the cantrips gained from dragonmarks are treated exactly like the other spells, which means their use is limited to once per day. I’m am not sure if I interpret this correctly, if this is intended this way, or just worded weirdly.

Are cantrips gained from Pact of the Tome considered warlock spells?

The warlock’s Pact of the Tome option for the Pact Boon feature says:

When you gain this feature, choose three cantrips from any class’s spell list. While the book is on your person, you can cast those cantrips at will.

Are these cantrips considered warlock spells for the purposes of determining attack bonuses and save DCs?

I think that might be the intent, but unless I’m missing something, I don’t think the rules as written support that. Similar features seem to specify when a spell becomes a class spell, such as a cleric’s domain spells:

If you have a domain spell that doesn’t appear on the cleric spell list, the spell is nonetheless a cleric spell for you.

Is my interpretation correct that while the warlock can cast those cantrips, they need to use the spellcasting ability of the class whose list the cantrip comes from when casting them?

How much on average does the Durable feat increase the number of Hit Points gained when spending Hit Dice?

There are other similarly mathy questions on this site such as “How much damage does Great Weapon Fighting add on average?” and “Are features that allow −5 to attack to get +10 to damage mathematically sound?” but I was wondering how the math pans out with the Durable Feat.

The feat states:

When you roll a Hit Die to regain hit points, the minimum number of hit points you regain from the roll equals twice your Constitution modifier (minimum of 2).

There are two interpretations for how the Durable feat could work “How does the Durable feat work?”, but for the purposes of this question I would like you to assume that “the roll” refers to the total of the die’s result and the Constitution modifier.

As the answers there explain, this means the feat is useless to those with a Constitution modifier of +1 but it prevents the alternative interpretation’s unusual case of a d6 Hit Die class with a +5 Constitution modifier gaining 15 Hit Points from spending a Hit Die whereas their normal maximum is 11.

This is also shown to be the intended way for the feat to work (thank to user @Rykara for finding this) as Jeremy Crawford has made this tweet:

If you have the Durable feat and spend a Hit Die to regain hit points, the minimum number of hit points you regain is equal to twice your Constitution modifier (minimum of 2 hit points). For example, if your modifier is +1, you regain a minimum of 2 hit points.

How much does this feat increase the average Hit Point gain?

When can a Barbarian, who has just levelled up, use the additional Rage gained from that level?

At certain levels, Barbarians gain additional Rages to use between Long Rests. My question is, when can these additional Rages be used? The PHB seems a little unclear on this.

PHB pg.48

Once you have raged the number of times shown for your barbarian level in the Rages column of the Barbarian table, you must finish a long rest before you can rage again.

This description doesn’t really seem to account for levelling up between long rests. With that, there seem to be two options:

  1. The Barbarian can use their additional Rage immediately after levelling up. In this option, the additional Rage comes in as an unused Rage. This option uses the idea that if a level 11 Barbarian has raged 4 times, he is out of rages. If after he finishes his 4th Rage, he levels up and becomes a level 12 Barbarian, he would then gain a 5th Rage that is unused. Being as he has only raged 4 times since his last Long Rest, it would stand that he would have 1 more Rage.

  2. The Barbarian must wait until after his next Long Rest to use his additional Rage. In this option, when a Barbarian gains a level and an additional Rage, it is accounted as apart of the Barbarian’s total Rages, not available Rages. This option is similar to a players Hit Points when they level, as in the player gains Hit Points to their Hit-Point Maximum, but not their Hit Point Total.

PHB pg.15

Each time you gain a level, you gain 1 additional Hit Die. Roll that Hit Die, add your Constitution modifier to the roll, and add the total to your hit point maximum.

Levelling mechanics at my table:

The Rogue gets their additional sneak dice right away. The same goes for the Monk and their additional Ki points. Casters, while they get their additional spell slots immediately on level up, they must wait until a rest (short or long depending on the class) and then prepare spells for any new level of spells they have gained (ie: they have 1 level 5 spell slot, but no prepared level 5 spells).

When knowing an individual’s plaintext password history, how much information is expected to be gained with a new password? Do we know this?

The premise: Knowing a persons password history should provide information to help when guessing a new password of theirs.

At an extreme end, with a password history of wildcats, wildcats1, then wildcats2, I’d guess there is less than 1 bit of entropy in their next answer.

At the other extreme end, someone with randomly generated passwords would lose no information in their history. From an information-theoretic point of view, I imagine this is something we can estimate using the large amounts of password history data available in the world.

Somewhere in the middle, a history of “wildcats!Reddit”, “crazydogs!Facebook”, “locobirds!Stackexchange” would give me some good ideas for a Twitter password, and would greatly reduce the entropy of their hash. Of course, this would be related to the concept of password strength.

I’m not so well-read on security, but I assume my idea is not unique. Is there a name for this concept? Do we know any real-world values for the amount of information gained / entropy lost?

How to explain an ancestral guardian’s spirit features suddenly gained at level-up? [on hold]

I’m a new DM leading a 5e campaign with new players. Most of the characters, who are a cleric, two druids, and a fighter, do not gain weird new powers when they level up.

But the barbarian (still level 2) chose the Path of Ancestral Guardians, and when he gets to level 3, he unlocks the “Shaman King” spirits. I don’t know how to explain that in a “narrative” way.

I was thinking to have a random spirit enter his body while he is still level 2. He should not recognize anything at first, just his axe feeling lighter.

Later in the game the spirit will come out and help the barbarian while fighting. Later on the spirit will “grow” and acquire his old power and wisdom more and more, so I can explain the power-ups and “Consult the Spirit” (level 10 ability), and will eventually remember his past, as a great barbarian who fought something cool.

Is this the right way to explain this feature?

Can I use Megamagic (or other spellcasting features) on a spell that I gained from multiclassing? [duplicate]

This question already has an answer here:

  • Does a sorcerer's metamagic work for non-sorcerer spells? 3 answers

As I understand it, class features only apply to spells you gained through that class. For example, I can’t use the Distant Spell metamagic on, say, Cure Wounds, if I gained Cure Wounds from being a bard. Am I correct in this?

Speaking as both a player and DM here. I wanna know what I can build around.