This creature is supposed to be a miniboss in one of my adventures with a dark horror theme. It's intended to be a hard encounter for four 3rd level pcs.

The questions:

  • Is this monster actually a CR 5 monster according to the guidelines for creating monsters as set by WoTC?
  • Is the statblock generally consistent?
  • Is there information that is missing that needs to be included?
  • Are there contradictions that I'm missing?
  • Is it overly similar to or a copy of an existing monster?

My thoughts so far:

  • yes, it is a CR 5 monster. It might have relatively low hit points considering it's AC, (as compared to CR 5 monsters from this site, but it makes up for it with high damage output from it's lair action.
  • I saw no inconsistencies upon my review of the statblock
  • I can see no additional information needed
  • I did not notice any contradictions
  • I know of no monsters that are overly similar or the same

Prompts used:

All of this is done with GPT-4, available to ChatGPT plus users

how much do you know about dnd 5e monster stablocks? after you answer that, make a plan to create a monster statblock template. consider formatting, including headers, tables, and any other formatting you think is relevant, as well as ALL of the information you need to include. then execute that plan

The AI generates a template after creating a plan. Having the AI create a plan beforehand results in higher quality answers.

Given this plan and template, create a monster stat block for a single monster encounter that is a hard level encounter for four 3rd level PCs.

The AI generates the stat block given here, provided as markdown file. Some mild formatting changes were made.

The monster:

Venomous Shadowbeast

A stealthy and venomous creature that lurks in the darkest corners of the world.

Medium Monstrosity, Neutral Evil

Armor Class 15 Hit Points 68 (8d8+32) Speed 40 ft., climb 30 ft.

16 (+3) 18 (+4) 18 (+4) 10 (+0) 14 (+2) 8 (-1)

Saving Throws

  • Dex +6
  • Con +6


  • Stealth +8
  • Perception +4

Damage Resistances

  • Cold
  • Necrotic

Condition Immunities

  • Poisoned


  • Darkvision 60 ft.
  • Passive Perception 14

Languages: Understands Common, but can't speak

Challenge: 5 (1,800 XP)


  • Shadow Camouflage: The Venomous Shadowbeast has advantage on Dexterity (Stealth) checks made to hide in dim light or darkness.
  • Poisonous Blood: When the Venomous Shadowbeast is hit by a melee attack, the attacker must make a DC 14 Constitution saving throw. On a failed save, the attacker takes 7 (2d6) poison damage and is poisoned for 1 minute.


  • Bite: Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) poison damage.
  • Shadow Strike: Ranged Spell Attack: +6 to hit, range 60 ft., one target. Hit: 14 (4d6) necrotic damage.


  • Retaliate: When the Venomous Shadowbeast takes damage from a creature within 5 feet of it, it can make a bite attack against that creature.


  • Shadowy Grasp: The Venomous Shadowbeast causes tendrils of shadow to reach out from the darkness. Each creature within 10 feet of a point in darkness that the Venomous Shadowbeast can see must make a DC 14 Dexterity saving throw. On a failed save, the creature takes 10 (3d6) necrotic damage and is restrained until the end of its next turn.
  • 6
    \$\begingroup\$ Do you think it is? Have you done an analysis first to see how it works and what may be an issue? What were the prompts that you gave the AI? What new guidelines are you referencing for Monster creation? \$\endgroup\$
    – NotArch
    Apr 27, 2023 at 20:48
  • 2
    \$\begingroup\$ @NautArch Made an edit Addressing your points. Hoping someone with experience than I do can take a look over it. \$\endgroup\$
    – Jasmine
    Apr 27, 2023 at 21:07
  • 3
    \$\begingroup\$ Does the AI understand the difference between poison damage and the poisoned condition? I'm assuming that most monsters immune to the condition would also be immune to damage, or at the very least resistant? \$\endgroup\$
    – Kirt
    Apr 27, 2023 at 21:33
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    \$\begingroup\$ @Kirt "understand" is a hard concept to define in this case. If I asked the AI directly it absolutely does understand. When doing this I haven't primed it to remember that detail. I certainly think it might be an oversight \$\endgroup\$
    – Jasmine
    Apr 27, 2023 at 21:55
  • 1
    \$\begingroup\$ Have you tried to ask ChatGPT those questions? Would be interesting to see how it understands itself. \$\endgroup\$ Apr 28, 2023 at 12:11

1 Answer 1


Technically: CR6 in its lair, CR4 out of its lair, CR2 out of its lair against ranged attackers

The table here tells us that a CR5 monster should have proficiency +3, AC15, 131-145hp, +6 attack, 33-38dpr, and a DC15 save.

This monster has proficiency +2, AC15, hp68, +6 attack, and the damage is a little bit complicated:

  • bite attack 17 damage
  • retaliate bite attack 17 damage
  • assume 2x poisonous blood per round, 14 damage
  • assume 2x shadowy grasp per round, 20 damage

which comes to 64 damage per round as an estimate.

The defensive CR is 1.5 (68hp corresponds to CR 1/2, but plus one for having higher AC).

The offensive CR is 10.

Averaging the two numbers gives CR6.

Outside of its lair, the offensive CR is only seven, and the average CR is four.

Outside of its lair and if nobody is trying to melee-attack the monster, the offensive CR is three and the average CR is two.

This monster is pretty biased against melee attackers

The poisonous blood trait, in particular, is basically telling melee attackers not to bother. Ten damage per attack, and it gives the poisoned condition? And attacking gives the monster a free bite retaliate once per turn? Melee characters will feel tempted to pull out their javelins, or to stand in the monster's face and take the dodge action and hope their allies kill it.

Depending on your group, this could be a fairly easy fight (if they're all ranged attackers, blasting a monster that only has 68hp, and especially if they all have light sources). Or it could be fairly difficult if they're all melee attackers.

But the most likely way this will go is that your melee characters run into battle unawares, get chewed up by the monster's incredible retaliation traits, and then the ranged attackers try to kill the monster before the melee characters fail their death saves.

GPT4 shows decent rule comprehension

The derived skills and saves seem consistent assuming a +2 proficiency. The monster's bite attack seems to assume a +3 proficiency (using its STR mod?), and I'm unsure what stat is generating the +6 spell attack.

If the Poisonous Blood trait and Shadowy Grasp action were written whole-cloth by GPT4 (as they appear to have been) then GPT4 is doing a great job of writing valid 5e rules.

  • \$\begingroup\$ There are some discrepancies between bonus values and ability modifier/proficiency bonus, but I wouldn’t have expected the machine to grasp that nuance. \$\endgroup\$ Apr 27, 2023 at 21:26
  • \$\begingroup\$ If the lair damage tips the CR to 6, then both you and GPT should note separate CR numbers for encounters outside and within the lair, as is done, for example, with a demilich. \$\endgroup\$
    – Kirt
    Apr 27, 2023 at 21:39
  • \$\begingroup\$ Okay, seems fair. \$\endgroup\$
    – Dan B
    Apr 27, 2023 at 21:47
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    \$\begingroup\$ @Kirt and DanB: upon submitting this prompt to gpt-4 "Do an analysis of this monster and determine if it is biased against ranged or melee attacks, if it's CR is correct, including factors like whether it is in it's lair, and check for contradictions or inconsistencies. Then Self reflect on whether there are other improvements you can make. Once you've done this, please create a plan to fix any errors you find, then execute that plan", It correctly identifies this as a CR-6 creature in it's lair with bias towards melee combat, but does NOT identify two separate CR values. \$\endgroup\$
    – Jasmine
    Apr 27, 2023 at 22:07
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    \$\begingroup\$ I don't know. It wrote up a very generic-sounding, horribly unbalanced monster that averages out at CR 6, not CR 5 and which probably only seems to (almost) mathematically be consistent because there are some published monsters with similar stats. \$\endgroup\$
    – Obie 2.0
    Apr 29, 2023 at 2:58

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