What happens when a banished creature would return to an extradimensional space that no longer exists?

Consider the following scenarios.

1. Banished from a portable hole, portable hole is destroyed.

A portable hole is described as a ten foot deep, six foot diameter extradimensional space. Suppose I jump into my portable hole after spreading it out on the ground, and I am followed by an enemy. Once we are both inside my portable hole, I cast banishment:

If the target is native to a different plane of existence than the one you’re on, the target is banished with a faint popping noise, returning to its home plane. If the spell ends before 1 minute has passed, the target reappears in the space it left or in the nearest unoccupied space if that space is occupied. Otherwise, the target doesn’t return.

My enemy is banished to its home plane. Next, I climb out of my hole, get a safe distance away, and toss in my bag of holding:

Placing a bag of holding inside an extradimensional space created by a handy haversack, portable hole, or similar item instantly destroys both items and opens a gate to the Astral Plane.

The portable hole is destroyed, and finally I break my concentration on banishment before the full minute has passed.

2. Banished from a rope trick right before the spell ends.

Rope trick says:

an invisible entrance opens to an extradimensional space that lasts until the spell ends. […] Anything inside the extradimensional space drops out when the spell ends.

So I cast rope trick while I’m being chased, and my pursuer pursues me into my little rope trick room, where I am patiently holding banishment. I banish my pursuer, climb out of my rope trick room, and and cast dispel magic on the rope:

Choose one creature, object, or magical effect within range. Any spell of 3rd level or lower on the target ends.

Again, no space to return to as I break my concentration on banishment before the one minute is up.

What happens to the banished creature when banishment ends? Banishment is very specific that the creature returns to the space it left from. Both the actual extradimensional space and the 5 foot square space the creature previously occupied is gone, as well as all nearest unoccupied spaces. What happens?

Does a creature possessed by intellect devourer have blindsight?

The intellect devourer’s feature Body Thief says the following:

While inside a creature, the intellect devourer has total cover against attacks and other effects originating outside its host. The intellect devourer retains its Intelligence, Wisdom, and Charisma scores, as well as its understanding of Deep Speech, its telepathy, and its traits. It otherwise adopts the target’s statistics.

Does it retain its 60ft blindsight and immunity to the blinded condition while inside the creature?

Can a creature kill itself by dashing during a chase?

DMG p.252

During the chase, a participant can freely use the Dash action a number of times equal to 3 + its Constitution modifier. Each additional Dash action it takes during the chase requires the creature to succeed on a DC 10 Constitution check at the end of its turn or gain one level of exhaustion.

Suppose a creature was in a chase and already at Level 4 of exhaustion. It chose to continue dashing and at the end of its turn failed its constitution check.

DMG p. 252

A participant drops out of the chase if its exhaustion reaches level 5, since its speed becomes 0.

Now suppose a creature that was [allowed to Dash twice on its turn] started its turn at exhaustion level 4 and chose to Dash twice. At the end of its turn, it would be required to make two Con checks. If it failed the first check and got to Exhaustion Level 5 would this immediately remove it from the chase and thus remove the need to check again, or would a second check still be required with the possibility of death if it failed?

Note that exhaustion from chases has a different recovery mechanic than other exhaustion, in that (DMG p. 252)

A creature can remove the levels of exhaustion it gained during the chase by finishing a short or long rest.

whereas exhaustion gained by other means requires a long rest, food, and drink. Thus there is some evidence that while chases are temporarily exhausting, the exhaustion gained from them is not as serious or as lasting. Might this include the chase-induced ‘death’ as well?

Creature telepathy and illusions?

I am running a D&D 5e campaign, and we had an interesting case come up in play last night.

The party cast minor illusion to conceal themselves in a cave at the end of a narrow canyon, and then a Spined Devil, with telepathy, spoke to them telepathically (and they replied).

Does the presence of the illusion mean that the Spined Devil could not have known telepathically that they were there?

In other words, since the party had been conversing while within the Spined Devil’s telepathic range, even though he was out of sight and ear shot, would there be any reason to think that he would not be able to ascertain their (general) location despite the illusion, once he arrived at that location?

Does a creature under the effect of Motivational Speech still get advantage on their next attack if the spell ends for them?

The spell motivational speech (Acquisitions Incorporated, pg. 77) says:

For the duration, each affected creature gains 5 temporary hit points and has advantage on Wisdom saving throws. If an affected creature is hit by an attack, it has advantage on the next attack roll it makes. Once an affected creature loses the temporary hit points granted by this spell, the spell ends for that creature.

So when the effected creature is hit by an attack, the spell grants the creature advantage on their next attack. But getting hit by an attack is going to be accompanied by damage – and 5 points seems like it will very often be gone with a single attack.

Does a creature hit by an attack still get advantage on its next attack if that attack dealt 5 or more damage? Or does the spell end for them immediately and they do not get advantage on the next attack?

It just seems like this effect is going to be self-defeating a lot of the time – the thing that grants the advantage is the thing that takes it away. Am I missing something?

Note, temporary hitpoints are always lost first, so no holding on to them while subtracting damage from your standard hitpoint pool. Sorry Jim, it was a clever thought.

In 5e, can “creature” and “character” be used interchangeably?

Creatures in 5e is a general term covering all living entities, from NPCs to PCs, wolves to level 20 gnome wizards. Monsters, characters, and NPCs are all creatures.

Monsters are creatures with a stat block, such as wolves.

Characters on the other hand appears to only refer to PCs with a character sheet, such a level 20 gnome wizards.

We also have NPCs, which are otherwise monsters, but the DM is using them to interact with the party socially.

I see some evidence of this in various sections. For example the proficiency bonus section states "Characters have a proficiency bonus determined by level, as detailed in "Step-By-Step Characters." Monsters also have this bonus, which is incorporated in their stat blocks."

This quote from the difficulty class rules states:

If the total equals or exceeds the DC, the ability check is a success–the creature overcomes the challenge at hand. Otherwise, it’s a failure, which means the character or monster makes no progress toward the objective or makes progress combined with a setback determined by the DM.

Are these definitions correct?

Is there a slowest creature in D&D, if so which?

Based off of my other question What creature or vehicle has the fastest unmodified speed?, I’m wondering if there is a possibly a slowest creature in D&D 3.5e?

I am looking for basic speed, no modifications of any kind: magic, psionics, levels, templates, feats, whatever. Just unmodified as-it-is-printed. Something that I can point to.

Unlike my other question, just creatures, not vehicles.

Polymorphing into a creature that is larger than the room

If a character has the ability to transform into different creatures (using polymorph or wildshape as examples), what would happen if they shift into a creature larger than the space they are in?

Example: a chartacter is in an 8x8x8 room and turns into an elephant via any shape changing spell/ability.

Would the polymorph or wildshape still take effect?

Would the character take damage and if so how would that be determined?

Would any other creatures in that room take that same amount of damage?