Is the negative energy plane underneath Golarion?

I had always been under the impression that Golarion and the negative energy plane were on entirely different metaphysical planes. This would mean that you couldn’t simply move from one to the other using mundane means.

The Tar-Baphon entry on Lost Omens: Legends says (pg.104):

Tar-Baphon dug a portal to the Negative Energy Plane on the Isle of Terror …

To me, this sounds like he physically dug a hole to the negative energy plane. At face value, this would only be possible if the negative energy plane were somehow underneath the earth of Golarion.

I have access to many of the PF2 books, but am weak in lore published in PF1 resources. Is it true that the negative energy plane is literally below Golarion?

Do negative modifiers change a critical hit? [duplicate]

I want to play a champion fighter and am considering whether or not to get the Great Weapon Master Feat which states:

Before you make a melee attack with a heavy weapon that you are proficient with, you can choose to take a – 5 penalty to the attack roll. If the attack hits, you add +10 to the attack’s damage.

If I take the -5 to attack roll and roll a critical hit, will that crit still be in effect, or will the -5 counteract that? Also, in the event that I do crit with a -5, would I add the +10 damage before, or after I double damage, like with other modifiers. It doesn’t say that the +10 is a modifier specifically, so I was a bit confused (note: for critical hits, my group usually has house-rule to double the damage and then add modifiers instead of the normal double dice.)

Does reducing a character’s max HP with a spell also reduce the “negative HP” threshold needed to cause instant death?

Here’s my situation: In a fight with a group of vampire thralls, the party’s wizard got caught in a corner and was being savaged by vampire bites, his max HP dropping from 24 to 11. They fended off the vampires, but the wizard was at 3hp (He refused to be healed by the cleric due to his character’s hatred of religion and gods). He activated a trap collapsing the temple, and ended up getting hit by a falling chunk of stone ceiling, taking 15 damage (the rock rolled better than any of the vampires).

Now, the wizard is reduced to 0 hp, with 12 damage left over. The cleric’s player says that exceeds the wizard’s current max hp of 11, causing insta-death. The wizard’s player argues that the death threshold for negative HP isn’t affected by max-hp-reducing spells, claiming that would make those kinds of spells more powerful than intended.

I have stories planned in either case, but I’d rather be certain that I’m following the rules.

Is the threshold for instant death based on current max hp or normal max hp?

Adder-Subtractor Circuit With Negative Results

So, I understand how binary arithmetic works, and I understand how an adder-subtractor works for signed numbers. There is only one thing I am not sure about:

All the cases work ok in the circuit I have, except if the result of a subtraction is negative, I need to take the two’s complement of the output byte to get the actual result. What can I do about it? Do I need an extra array of adders to compute the two’s complement only in that specific way, or is there any smarter solution I can apply?

Thanks in advance.

Can a tarrasque be animated by negative energy flood? [duplicate]

The spell negative energy flood says:

"You send ribbons of negative energy at one creature you can see within range. Unless the target is undead, it must make a Constitution saving throw, taking 5d12 necrotic damage on a failed save, or half as much damage on a successful one. A target killed by this damage rises up as a zombie at the start of your next turn. The zombie pursues whatever creature it can see that is closest to it. Statistics for the zombie are in the Monster Manual. If you target an undead with this spell, the target doesn’t make a saving throw. Instead, roll 5d12. The target gains half the total as temporary hit points"

It does not specify the creature must be humanoid nor the size of the creature. However, it implies the new zombie’s stats must be in the MM. Can a tarrasque be animated by this spell’s effect?

Do negative Hit Points exist in D&D 5e?

Say that a character has 5 HP remaining and is dealt 10 damage from an attack. Of course, 5 – 10 = -5, so the character has dropped below 0 Hit Points and follows the rules for making death saving throws (provided they didn’t get dealt enough damage for instant death). However, it’s not clear to us if the character remains at -5 Hit Points or if they bounce back up to 0 Hit Points (like many rules in 5e, knowledge of past editions may be a hindrance to interpreting them).

If negative Hit Points exist, then characters will take longer to recover naturally (since stable characters recover at a rate of 1 HP per 1d4 hours). Also, a natural 20 on a death saving throw, which recovers one Hit Point, would not make them instantly conscious. Finally, it would mean that instant death is a greater possibility, as you need less to reach the threshold if you are attacked again.

However if negative Hit Points do not exist and characters bounce up to 0 after crossing the 0 HP threshold, then characters will always regain 1 HP and become conscious after waiting 1d4 hours or rolling a natural 20 on a death saving throw. Also, this would mean that instant death is far less likely because someone who attacks an unconscious character would always need to deal maximum HP damage or they don’t kill you (and if they don’t, then I guess their damage means nothing, which seems rather odd).

Unfortunately, the example provided with the basic rules isn’t helpful because it describes someone taking enough damage for instant death, but not someone who got less than that. Furthermore, the rules describe “Dropping to 0 Hit Points”, but not “Dropping Below 0 Hit Points” and seems to omit what happens when you take more damage than the HP you have remaining, but less than enough for Instant Death. Our group spent a while debating this when we played from the Starter Edition and we weren’t sure given that some previous versions of D&D had them while others didn’t. So do negative hit points exist or do characters “bounce up to 0 HP”?

Do you include the constitution modifier to your starting HP if it’s negative?

When I was creating my Bard with a standard array, I considered making constitution my lowest.

I know that starting HP = the highest number of your class’ hit dice + CON mod (so 8 + CON for a Bard)

But I’m wondering if that formula still applies if the modifier is negative. My friend says it doesn’t, and I’ve tried looking it up, but all I get is if it affects your HP leveling up, not your staring HP

Is this addition to the spell Negative Energy Flood balanced?

In this question I outlined an inconsistency in the RAW interpretation of the spell Negative Energy Flood (XGtE, pg. 163): a size Large or larger creature killed by it rises as a size Medium zombie. To remedy this, I have added to the spell description to make it scale with the size of creature killed. Bold in the spell description indicates my addition to the spell.

Negative Energy Flood

5th-level Necromancy
Casting Time: 1 Action
Range: 60 feet
Components: V, M (a broken bone and a square of black silk)
Duration: Instantaneous

You send ribbons of negative energy at one creature you can see within range. Unless the target is undead, it must make a Constitution saving throw, taking 5d12 necrotic damage on a failed save, or half as much damage on a successful one. A target killed by this damage rises up as a zombie at the start of your next turn, having the same size and shape as the target. If the zombie is of size large or larger, it deals extra dice of damage on a hit. Double the weapon dice if the zombie is Large, triple the weapon dice if it’s Huge, and quadruple the weapon dice if it’s Gargantuan. Statistics for the zombie are in the Monster Manual. The zombie pursues whatever creature it can see that is closest to it.

If you target an undead with this spell, the target doesn’t make a saving throw. Instead, roll 5d12. The target gains half the total as temporary hit points.

This solves the obvious problem of Gargantuan creatures becoming Medium zombies, and I anticipate a size change alone has little implications for balance – correct me if I am wrong.

Potential balancing issues arise in increasing the damage output for Large and larger zombies. I borrowed the language directly from DMG pg. 278 in the section on creating your own monster stat blocks, taking into account the size of the monster. Step 11 of Creating a Monster Stat Block reads:

Big monsters typically wield oversized weapons that deal extra dice of damage on a hit. Double the weapon dice if the creature is Large, triple the weapon dice if it’s Huge, and quadruple the weapon dice if it’s Gargantuan.

A zombie has a Slam attack that deals 1d6+1 damage on a hit (Monster Manual, pg. 316). So for a large zombie, the damage on a hit would be 2d6+1, Huge 3d6+1, and Gargantuan 4d6+1.

I don’t think only scaling the damage dice by size would make the spell too much more powerful than it already is, the zombie still has an AC of 8 and 22 hitpoints. What would start to tip the scales out of balance, I think, would be scaling the hit dice according to Step 8 in the same section of the DMG (pg. 276), especially for Gargantuan creatures. Scaling hitpoints in this way gives: Large – 25 (3d10+9), Huge – 28 (3d12+9), and Gargantuan – 40 (3d20+9).

Allowing the spell to scale hitpoints in this way for Gargantuan creatures gives the zombie nearly twice the staying power as the original version of the spell did. I also couldn’t think of a clear way to word it into the spell description. For this reason, I propose only scaling the damage dice for the zombie with the zombie’s size.

Is this buff to Negative Energy Flood still appropriately balanced as a 5th-level spell?

Does a size large or larger creature killed by Negative Energy Flood rise as a medium sized zombie?

The spell Negative Energy Flood (XGtE pg. 163) states:

A target killed by this damage rises up as a zombie at the start of your next turn.

And also,

Statistics for the zombie are in the Monster Manual.

This seems to imply that the creature killed rises as a zombie with exactly the statistics stated in the Monster Manual.

If I kill a gargantuan (or anything larger than medium) creature with Negative Energy Flood, does it rise as a size medium zombie?