Today’s post is a continuation of A Guide to the Blasted Lands, which was itself a follow-up to Stat Boost: Some Books and their Contents. In the last post I gave you a map of the Blasted Lands and a small writeup of some of the key areas. In this post I’m going back to the Bestiary from the Stat Boost post, with full stats for three of the monsters from that post and one new one. And rather than just drop some monsters on you, I also want to talk for a little bit about building monsters in 5e, and about some of the considerations and decisions that went into making these things.
Let’s get to the monsters rather than continuing to bury the lede, because I know many of you will only care about them (and that’s perfectly fine – the rest of this post is pretty long).
Here be monsters:
I hope you enjoy them, and if you end up using them I hope you’ll let me know.
Now, let’s talk about building things.
Shortly before I finished building the last monster for this post – the Living Dune – I posted its ‘Living Terrain’ trait on Twitter for some feedback. Josh Parry – who is a talented DMs Guild creator, by the way – pointed out that it sounded like the Dune Mimic from Kobold Press’ Tome of Beasts. I have that book, and though I’ve never sat down and read it all the way through I’ve definitely made use of some of the monsters in there (I love the Cobbleswarm, and my last session featured a Void Dragon). I didn’t immediately recognise the Dune Mimic, and I don’t think I’d seen it before I built the Living Dune. That said, the similarities are definitely there, and since I’ve used the Tome of Beasts I can’t guarantee that I haven’t seen it before and that I wasn’t influenced by it in some way. I also noticed when looking at the Dune Minic that there’s also a creature in there called a Cactid that bears a resemblance to my Cacanid.
I didn’t set out to rip off Kobold Press, but I’m clearly working in the same design space as them whether intentionally or not. Hopefully my creatures are different enough from theirs that nobody will immediately assume that I stole them (though the similarity of cactid and cacanid is, I admit, an unfortunate coincidence).
The Monster Mash
There are two basic routes you can go down when creating new monsters. The first is to take an existing monster and tweak it; the second, obviously enough, is to invent something entirely new. With these monsters, I’ve done both (though I’ve attempted to swing the balance in favour of entirely new creatures).
One of the most obvious tweaks to an existing monster lies in the flowering mound, which is a shambling updated to exist in the weird deserts of the Blasted Lands rather than the fetid swamps in which they are more usually encountered. Building this thing was an interesting process, and it taught me quite a bit about the relative fluidity of challenge ratings. I want to take a minute to talk you through the design of this monster and some of the decisions that I made, in the hope that it might prove useful to you if you’re thinking of trying your hand at monster design.
The first thing I did was to look at how the shambling mound is constructed in terms of challenge. If you’ve read Angry GM’s Monster Dissection Lab (and if you haven’t, you should), you’ll know that the challenge of a creature is calculated from the average of its Offensive CR (OCR from hereon out) and Defensive CR (DCR). This isn’t always an exact science, though, and the shambling mound is a good example of this.
When looking at a straightforward CR 5 creature (i.e. one where both its OCR and DCR are 5), we’d expect to see the following range of stats:
- AC 15
- 131-145 HP
- +6 Attack Bonus
- Average of 33-38 damage per round
- Save DC 15
Let’s compare that to what we find with the shambling mound:
- AC 15
- 136 HP
- +7 Attack Bonus
- Average of either 30 damage/round or 35 damage/round
- Save DC 14
Let’s start with the damage calculation, because you have to make some assumptions here. In the first round, we assume the mound hits a creature with two slam attacks (13 + 13 damage = 26 damage) and engulfs it. In the second round, the engulfed creature takes 13 damage and the mound hits with another two slam attacks, for a total of 39 damage dealt. In the third round, we assume the engulfed creature has escaped and the mound hits with another two slam attacks, dealing 26 damage. That’s a total output over 3 rounds of 91 damage, averaging to 30.
Alternatively, we can assume that the engulfed creature doesn’t escape the mound and takes the damage again on the third round. This raises the overall damage output to 104, averaging to 34.6. The mound’s Save DC is lower than we’d expect for a CR 5 creature, though, so I think it’s safe to assume that the engulfed creature will escape.
So, looking at the shambling mound, its AC and Hit Points are what we’d expect them to be, but its damage output is slightly lower than we’d expect and saving throws against it are easier than we’d expect. It does hit more often than we’d expect it to with that higher attack bonus, though.
Neither the damage output or the saving throw are really that much lower than expected for us to drop either the OCR or the DCR, and they’re balanced by the fact that it hits regularly and has the ability to take an enemy out of the fight for a third of the battle.
We should also note that the mound has multiple resistances – to cold and fire, plus immunity to lightning – which could potentially mean that we should treat it as having higher effective hitpoints. It isn’t resistant or immune to bludgeoning, piercing, or slashing damage (the most important types), though, and even though it absorbs lightning and heals from it, that trait alone doesn’t affect any of the effective stats (because players are only going to use lightning against it once, if at all). Those things do stack up, though, so it might be worth raising the effective hit points to 1.5x the total.
In that case, the shambling mound has 204 effective hit points. 204 HP gives us a Defensive Challenge of 9, for which the expected AC is 16. The mound has an AC of 15, so really we should assume that the Defensive CR is 9. And, interestingly enough, the Attack Bonus for CR 9 is +7 – the same as our shambler.
Personally, I don’t think the designers calculated the shambling mound’s stats with increased effective HP. With them, the shambling mound works out more like CR 8 or 9 (the mound’s Save DC is 2 points lower than we’d expect at 9, and its Proficiency Bonus is +3, not +4, which is why I say 8 or 9). Without them, the mound sits pretty comfortably at CR 5.
So, how does this pertain to the design of the flowering mound? I kept all this in mind going into designing the flowering mound. I knew that I wanted it to be slightly bigger and badder than the shambler, but not ridiculous, and that I wanted fights with it to feel different to fights against a shambler. I envisioned it being CR 6, and I found very quickly that simply going up one level of CR gave me enough room to add the features I was thinking of.
When you fight a shambling mound, you’re usually in a very close, tight swamp-like environment with minimal visibility, and the mound will often get the jump on you (that’s what that +2 to Stealth is there for). In the case of the flowerer, you’re going to be out in the desert – there aren’t many places for a slow plant creature with bright flowers on it to hide out there, and I actually got rid of the Stealth skill because the creature simply has no use for it.
Instead, I wanted to do two things – first, to add some piercing damage to its Slam attacks to account for the fact that it’s covered in thorns, and I wanted to give it a mechanism that would allow it to close the distance with its foes and engulf them. Specifically, I pictured it opening up its flowers and releasing a cloud of pollen that would paralyse nearby foes, allowing it to get into melee range and start eating people.
I thought that this ability would massively complicate matters due to the fact that successful attacks against paralysed creatures are automatically crits. I wondered if it would be better to change this to a Stun effect – granting Advantage on attacks, rather than automatic crits – but first I wanted to see how paralysis played out. It turns out, though, that that bump from CR 5 to CR 6 leaves enough room in the numbers for both the piercing damage and that paralysis mechanism – if you’re careful.
At CR 6, we expect to see the following:
- AC 15
- 146-160 HP
- +6 attack bonus
- 39-44 DpR
- Save DC 15
Initially this seemed fairly straightforward. The piercing damage was easy: the cactus-like spines covering its body aren’t particularly large – they’re more of a nuisance than anything, a little bit of salt in the wound – so I decided that they would only deal 1d4 damage. That’s only an additional 2 damage on each attack.
To get from the shambler’s 136 (16d10 + 48) HP to our expected range, all I had to do was increase the flowerer’s Constitution to 18 (+4); 16d10 + 64 comes out to 152 HP, right in the middle of our ranger.
Then, I wrote the paralysing pollen effect. Initially my mound had a Save DC of 15 – because I’d increased its Constitution – and I had the pollen deal 9 (2d8) poison damage on top of the paralysis effect.
Then, I figured out some the average damage. Before I did the maths, I figured I was going to have to do some tweaking due to the critical hits. Then, when I was done, I figured that I actually didn’t need to tweak anything. I turned out to be wrong about that once I put some more thought into it, but bear with me.
We’re aiming for an average DpR of 39-44. On the first round, we’re going to assume that the mound affects two creatures with its pollen, dealing 18 damage total and paralysing them both. On the second round, it hits – and crits – with two slam attacks. Each of these attacks deals 2d8 (doubled) + 4 bludgeoning damage, and 1d8 (doubled) piercing damage. The maths for that looks like this:
That’s a total of 52 points of damage on round two, and the poor character is engulfed.
Round three begins with the engulfed creature taking 13 points of damage. We assume that the other creature who was paralysed has escaped that effect, and that the next two slams aren’t critical hits. In that case, those attacks deal 30 points of damage total, giving us 43 points of damage over the round.
So, what’s (18 + 52 + 43) / 3? It’s 47.6, or an average of 38 points of damage. So, we’re just shy of our expected range.
Increasing the piercing damage to 1d8 rather than 1d4 gives us totals of (18 + 60 + 47) / 3. That’s an average of 42 damage per round, which sits perfectly in range. So we’re done, right? Easy, right?
Wrong. Well, I think it’s wrong, anyway. This is where you kind of have to throw out the maths a little and go off intuition.
Firstly, look at the shambling mound. Its Save DC is lower than we’d expect at CR 5, so we can safely assume that the engulfed enemy is only in there for a round. In the case of the flowering mound, though, not only do we have another DC-based ability – the paralysing pollen – we also have a Save DC exactly where we’d expect it to be for this level. And, according to page 238 of the DMG, DC 15 is a moderate challenge. So the assumption that creatures who failed their saves the first time will pass the second time isn’t quite as safe.
This makes an encounter with a flowering mound much more dangerous. We’re assuming that two creatures are affected by the pollen, so in round 3 of combat we’re going the mound is going to be dealing crits against that creature, too. That changes our damage output dramatically; now it’s dealing that same 60 points of damage in round 3, with an additional 13 points to the engulfed creature. The average in this case is (18 + 60 + 73) / 3, which comes out at 50 points per round. That sits right at the top end of OCR 7.
There are a couple of ways to fix this, and I initially thought that the most obvious way of doing it would solve everything. That option was to drop the Constitution back to 16; this lowers our HP to the same as the CR 5 shambler, and lowers the Save DC to 14, meaning we can assume that there will only be one round of paralysis and one round of engulfing in 3 rounds of combat. That’s a nice, easy fix – slightly lowering the DCR to account for a high OCR.
You’ve probably already spotted the problem, though. That engulfed creature? She’s taking 73 points of damage in two rounds. That seems like a lot for a 6th level character. I wanted to know if I was potentially going to one-hit kill at least one member of the party in the first round of combat. That meant doing a little bit of maths, based on rather a lot of assumption.
I wanted to figure out how many hitpoints your average 6th level character might expect to have, but I really didn’t want to work that out for every class in the game. So I made some assumptions. The mound is slow and out in the open, so it isn’t likely to get the drop on the party like a shambler might. It certainly isn’t going to be sneaking up behind them (unless it attacks at night while they’re resting at an oasis – but without that Stealth bonus, they’re likely to hear it coming).
So, I assumed that the character getting paralysed, critted, and engulfed is a frontline character of some sort – namely, a barbarian, a fighter, a paladin, a monk, or maybe a ranger (who might be out front blazing a trail for the party). For the sake of ease, I assumed that all of our sample characters are Human, and begin with a +1 to Constitution. Then I looked at the suggested stats for those classes in the PHB and assumed that if Constitution was listed as a suggested score for that class, that character would make it either the highest or second highest score they had (based on the PHB’s suggestion). I assumed that characters would be built using the Standard Array, and that they each took an ASI of +1 in their main and secondary stat at 4th level. Then, using that information, I calculated average HP for each class using average rolls and rounding down:
|CON at 6th Level||16||16||16||15||15|
|Average HP at 6th Level||62||55||55||42||49|
Given those hit point totals, it seems pretty clear that our Flowering Mound is likely to kill the first creature it hits outright. I’m not averse to killing characters, but it should be a result of their poor planning or a failure on their part, rather than because a monster is built to one-hit them. So we need to dial it back a little.
The first and easiest change to make is to change the paralysis to stun, as I mentioned earlier. This negates the extra damage for crits (and stops me twitching about the fact that I spelled paralyse “paralyze” in the stat block, to fit with the conventions of the core rulebooks). Let’s put the Con and Save DC back up to their original values, and see where we are. We’ll also assume the engulfed creature and the second stunned creature fail their saves each time they make them.
On the first round the mound sprays pollen, dealing 9 points of poison damage to two creatures and stunning them. Total damage: 18.
On the second round the mound slams one creature twice with advantage. Let’s assume one crits. We’ll deal 29 + 17 damage and engulf them. Total damage: 46.
On the third round, the engulfed creature takes 13 damage. Then we make two slam attacks against the other stunned creature, again with advantage and again critting on one attack. Total damage this round is 59.
Over the three rounds we’re now dealing 123 points of damage, which works out to an average per round of 41.That’s still within our expected range, but much less lethal; it will still put a 6th level monk with average hit points below 0 in one round, but we’re also assuming that we’ve critted.
Let’s assume that we didn’t crit – because there’s only a 5% chance of that on each attack. In that case, our average damage is now 33. That’s actually lower than our expected value, but that’s also in line with the way the shambling mound works. Our attack bonus is still higher than expected, and with advantage we’re still going to hit most of the time. It still feels like a shambling mound – but now you also have to deal with the fact that more than one member of your party could be out of action at any given time.
All in all I’m pretty happy with how this thing turned out. I’m still yet to use it at the table, so I don’t know if it actually feels familiar-yet-different to parties who have faced shambling mounds before, but I’m pretty confident that the numbers are right and that this will pose a challenge to 6th level parties.
I went through a similar process with the Living Dune, too, and very quickly discovered that CR sort of falls apart mathematically once you’re at higher levels. I won’t go into quite as much detail here as I did with the Flowering Mound; suffice it to say that it’s hard to make a big, powerful monster like this and stick with the numbers. With an expected Proficiency Bonus of +5 and an Attack Bonus of +8, it becomes difficult to make a monster that will mostly deal in melee attacks that sits happily at that range. To stay within those numbers, the highest Strength score we can give the thing is 17 (+3). That’s ridiculous.
But look at some of the big CR 15 monsters in the Monster Manual. The Purple Worm (page 255) has an Attack Bonus of +9, but it also has a Strength of 28 (+9). So, we’re assuming that it isn’t actually proficient with its attacks, which is interesting.
Similarly, look at the Mummy Lord (page 229). I’ll admit that I had never really looked at this monster before, and I have Dan Dillon and @AndruC to thank for bringing this to my attention in this Twitter thread.
Once again it’s a CR 15 creature, but it has the HP of a CR 2 creature along with a vulnerability to fire that is almost certainly going to come into play at that high a level. It has the ability to take members of the party out of the fight for a few rounds at a time with that Dreadful Glare, and its Rotting Fist is no laughing matter – but the Save DCs are also lower than we’d expect at CR 15. The Legendary Actions let it put out a lot of hurt in a relatively short space of time – if you only used its Rotting Fist you’d put out a massive 140 points of damage over a full round of combat (which is at the top end of CR 20), compared to the expected 93-98 average damage at this challenge rating – and allow it to quickly get out of harm’s way while preventing enemies from healing, but really this thing is a massive glass cannon.
I’m not sure exactly what my point is here with regard to my Living Dune. Mainly, what I’m getting at is that CR is a weird thing and that it gets weirder at high levels, and that – as I’ve mentioned already in this post (I think) – some parts of monster design and balance falls to guy feelings rather than pure maths.
And with that, I’m going to end this post. I’ve talked for a very long time about this stuff now, and I’m sure you’re growing tired of it. If you made it this far, thanks for sticking with me.
As a reward for getting this far, I’m going to save you the job of scrolling back up to get to the actual monsters. Here they are again:
Thanks for reading; please do let me know what you think of these things!