Can a grappling creature cause a prone creature it is grappling to be unprone? [duplicate]

If my character is grappling a creature who has been knocked prone, that creature can’t stand back up unless they succeed in first breaking free of the grapple.

Do the rules for moving a grappled creature allow my character to cause the grappled & prone creature to stand up and stop being prone?

Moving a Grappled Creature. When you move, you can drag or carry the grappled creature with you, but your speed is halved, unless the creature is two or more sizes smaller than you.

What is damage you do vs. damage a creature takes? (and Dark One’s Blessing)

The Warlock ability Dark One’s Blessing says (emphasis mine)

Starting at 1st level, when you reduce a hostile creature to 0 hit points, you gain temporary hit points equal to your Charisma modifier + your warlock level (minimum of 1).

Is there a general ruling on who or what is the author of damage? Most spells and attacks are written to describe how the target takes damage, rather than how the attacker does damage. I think it is safe to assume that an attack you make or a spell you cast is you doing damage, but I am unsure on how to rule in a more abstract example, such as forcing an interaction with a damaging environment.

Consider the following hypotheticals. None of them are my specific question, but serve to illustrate what I am trying to come to terms with. My question is whether there is a general underlying principle in the game that assigns authorship to damage.

For example, suppose oil has been spread on the floor and a hostile creature chooses to cross it. My warlock throws a lit torch into the oil and the DM requires an attack roll. The subsequent fire reduces the creature to 0hp. Does the warlock get to use Dark One’s Blessing?

Suppose the same warlock lights a nearby patch of oil on the floor and the DM does not require an attack roll. A hostile creature later chooses to enter the burning oil and is reduced to 0hp. Does the warlock get to use the ability? Did he reduce the creature to 0hp, or did the fire? Does it matter that the creature chose to enter the fire through its own movement – if the warlock had been able to use a spell or action to force the movement, would the answer be different?

Finally, consider three warlocks who all have initiative before a target. One throws a flask of oil on the floor, one throws a torch that ignites the oil, and one uses a shove attack to move a hostile creature into the space where the flaming oil is / will be. Which warlock(s) get to use Dark One’s Blessing? Does their order matter? That is, is it a different answer if the shove moves the creature to the space where the oil will be, vs. to a space where the flame already is?

Possibly related: If my familiar is forced through my action to drop a rock while over a target, is it considered an attack?

What happens when a creature with Racial Hit Dice changes creature type?

The specific example I’m working with is a creature with RHD who takes the Human Heritage feat… and then advances by HD.

The creature retains all the traits of its previous type (so far so good), but what happens to its existing RHD? Do they change to the new type, or stay the same? The SRD says:

…but most templates that change Hit Dice change only the creature’s original HD and leave class Hit Dice unchanged.

However, this is in the context of whether class HD change when there is already an HD change happening, so I don’t know if it should generalize to "HD changing is the default".

If the creature then advances by gaining more HD, I assume that all the new HD would be of the new type, but I’m open to peoples’ opinions on this as well.

Bridging the two questions, there’s also an argument to be made that since Human Heritage is a 1st level only feat, all RHD are acquired after it is taken, and should thus be of the Humanoid type.

Does an out-of-sight creature affected by the Fear spell have to keep running if they fail the saving throw?

Imagine a (D&D 5e) spellcaster casts Fear on an enemy, and the enemy fails their Wisdom saving throw. On its turn, the enemy drops what it’s holding and takes the Dash action, running away from the spellcaster and around a corner, putting it out of sight of the spellcaster. The enemy ends its turn out-of-sight of the spellcaster, so it can make the Wisdom saving throw again; again, it fails. On its next turn does the enemy have to continue running away? Even though it’s out of sight of the spellcaster? My reading of the spell is yes: they have to continue to run away until they succeed on the save (or the spellcaster drops the spell for some other reason). Is this right, or can the enemy remain in place out-of-sight? (They obviously can’t approach closer to the spellcaster because they’re affected by the frightened condition.)

Can a frightened creature freely circle the source of its fear?

A frightened creature A is standing horizontally or vertically next to the source of its fear B.

The creature can’t willingly move closer to the source of its fear.

Can A freely circle B, for example to flank them or to attack another of its enemies, or to pass them with impunity in a 10′ hallway (subject to AOO rules as normal of course)?

I am asking, because this seems somewhat counter-intuitive: If you are next to the source of your fear, the fear does not practically restrict your movement. I hope there’s something in the rules or maybe sage advice which clarifies this, other than just lack of restrictions that would apply.

If a flying creature with no swim speed ends up in water, can it fly out?

Assuming there is no magic holding it aloft and it doesn’t have the ability to hover, when a flying creature is knocked prone, it falls.

What happens if the creature was flying over a body of water? Can it effectively use its movement to "stand up" on its next turn and resume flying, or does it end up like that video of the bald eagle swimming, where its feathers are too wet and it can’t reasonably get enough lift to take off again?

Ducks can take off from water, but I would argue that ducks have a swim speed.

Can a creature with multiple attacks per Attack action make all their attacks if they are incapacitated between two of those attacks?

The Player’s Handbook states (emphasis mine):

An incapacitated creature can’t take actions or reactions.

Suppose I am fighting a creature that has a multiattack, and I have an ability that can incapacitate a creature as a reaction. If the creature has completed the first attack in its multiattack, could I prevent the remainder of its attacks with my ability? Or is it too late, since the remaining attacks aren’t actions?

What spells or other effects cause a creature to make a saving throw to avoid being knocked out?

I saw that a hydra has "advantage on saving throws against being… knocked unconscious" and was curious as to what spells or effects would cause such a thing to happen. The only effect that came to mind is the sleep spell, which operates on hit points rather than a saving throw. What else can knock a creature unconscious?

If a creature spawns more creatures during the combat, how does it affect the challenge rating? [duplicate]

I’m trying to balance a combat encounter for my players (in this example 5th lvl, 10 characters). I want to use the Sword Wraith Commander (SWC) (MTF, p. 241). The SWC has a CR of 8 but with its call to honor ability, it can summon 1d4+1 sword wraith worriors (SWW) which have a CR of 3 each. One CR 8 monster is rated as a trivial combat encounter but adding five CR 3 monsters makes it deadly.

This raises the question: Is the ability to summon up to five CR 3 monsters included in the CR 8 rating (meaning the total combat with the SWC and up to 5 SWW has a CR of 8) or do we count the CR’s independently?