****ing Hit Dice, how do they work?

[ParanoydStyle]

So, I have combed the Dungeon Master's Guide and the Monster Manual, not exhaustively but pretty thoroughly, and for whatever reason I haven't been able to find where it tells you how it is determined how you calculate the number of hit dice that monsters and monster-like NPCs (for lack of a shorter label) have. There are the monster creation tables in the DMG but they don't seem quite consistent with the actual stat-blocks that I've seen, like maybe the methodology they're recommending isn't the one they actually used?

ANYWAY, my question is, how do you determine how many HD anything other than a PC or NPC-built-as-a-PC has in D&D 5E?

(The thread title was a reference to a very stupid music video by a very stupid band.)

 

[Azzy]

So, I have combed the Dungeon Master's Guide and the Monster Manual, not exhaustively but pretty thoroughly, and for whatever reason I haven't been able to find where it tells you how it is determined how you calculate the number of hit dice that monsters and monster-like NPCs (for lack of a shorter label) have. There are the monster creation tables in the DMG but they don't seem quite consistent with the actual stat-blocks that I've seen, like maybe the methodology they're recommending isn't the one they actually used?

ANYWAY, my question is, how do you determine how many HD anything other than a PC or NPC-built-as-a-PC has in D&D 5E?

(The thread title was a reference to a very stupid music video by a very stupid band.)

First, I'd suggest not ****ing your Hit Dice. They may not like it.

The monster creation rules focus on a spread of average hit points instead of hit dice. It's really up to you to determine how the average hp of a monster are expressed through hit dice, but remember that the size of hit dice is based on the monster's size (as noted in the the DMG, pg 276) and that their Con modifier... modifies the hp total. So if the average hp you're shooting for is in the range of, say, 50-70 and the creature is Large (d10 for HD), the you'd want to shoot for 9-12d10 with Con mod factored in. Or rather, you should just decide the HD and Con, and then calculate the CR from that.

 

[LordEntrails]

What Azzy said and then it's really pretty simple.

It's really very very simple; How many do you want your creature to have?

To add context or detail; Are you aiming for a specific Challenge Rating? Do you want them to have more or less than the average creature of the CR?

The way I do it is I usually start with a concept and a target CR. I make some rough estimates based on my concept and experience, then I figure out how it fits based on the tables in the DMG and how it compares to MM creatures and then adjust until I'm comfortable.

 

[abirdcall]

You choose.

Simple as that.

Monsters/NPCs don't follow PC rules.

You choose then you use DMG guidelines to approximate a CR.

 

[Charlaquin]

Step 1: decide how many hit points you want the creature to have. Call this Value A.

Step 2: figure out what hit die the creature has (this is determined by the creature’s size - d6 for small, d8 for medium, d10 for large, etc.)

Step 3: determine how many hit points the creature gains per hit die (this is equal to half the maximum number of the die, plus .5, plus the creature’s Con mod, so for example 6.5 for a medium creature with 14 Con). Call this Value B.

Step 4: divide Value A by Value B. Round as necessary.

 

[S'mon]

You could derive it from the creature's hp, size, and CON. Size determines hit die type. CON determines bonus. So eg for CON 15 (+2) medium (d8), it has 4.5+2 = 6.5 hp per hit die. Divide its hp by 6.5 to get the number of hit dice.

NB this only ever comes up if your monster is having a Short Rest to heal damage.

 

[77IM]

Another good trick is to look at a few similar monsters or NPCs and see how many hit dice they wound up with.

For example, looking at the NPCs:
- A commoner has 1 HD
- A guard has 2 HD
- A scout has 3 HD
- A thug has 5 HD
- A priest also has 5 HD, but winds up with a lot fewer HP because of lower Con
- A spy has 6 HD
- A knight has 8 HD
- A mage also has 8 HD, but winds up with a lot fewer HP because of lower Con
- etc.


Why do those characters have that many HD? Well, that's just how tough they are. You don't need to explain it. Presumably, the knight has more "experience" than the thug who has more than the guard. If a troll has 8 HD also, does that mean he has as much experience as the knight? No, it just means that his overall combat toughness is equivalent to a knight (or, more reasonably, a knight is a person who's got enough moxie to go toe-to-toe with a troll).

So if you are creating an NPC who you think is probably a bit tougher than a common thug, but maybe not as badass as a full-on knight, give that NPC 6 or 7 HD.

 

[aco175]

Remember that you want to look at CR and hit dice. If my party is 5th level and I want to throw one monster at them, I would look at a CR5 monster which may have 10HD to give it enough hit points to survive a couple rounds. Knowing that one monster is not a good encounter, I want to make one big monster and a couple smaller ones to make a good fight. I would take a CR4 monster and a couple CR2-3 monsters to round out the fight. I also need to look at the type of monster they are, such as brutes with lots of HP, or ranged type with good offense at a distance.

I sometimes even cheat with the hit points/hit dice. If I plan a cool encounter with a giant and some goblins and the PCs fireball the goblins and are about to kill the giant before he even goes- the giant may suddenly have enough HP to make at least one attack. Typically this may be poor planning on my end or great rolls/luck by the PCs. The players do not know and I find they still like the encounters.

 

[MaximusArael020]

This website might be helpful in helping you figure it out. It's a great resource, and this page specifically has a lot of interesting information about monsters and how they are made in D&D 5e.

https://theangrygm.com/monster-building-201-the-dd-monster-dissection-lab/

 

[ParanoydStyle]

Awesome guys, thanks, this will be a great help.

First, I'd suggest not ****ing your Hit Dice. They may not like it.

Oh, I took a lol at this but in case anyone didn't know, I was referencing the infamous Insane Clown Posse video/lyric "Effing magnets, how do they work?" where they express childlike awe and wonderment at a well understood and documented scientific principle.

(They don't say 'effing'.)