Homebrew monster idea

[SnowPlowMan]

I have a creature that I built recently and I need some help balancing it before I destroy my Players with it. Not sure if the CR is to high or to low. Any input is helpful.

The general idea is its a swarm of bugs that are indistinguishable from treasure and sneak attack the party when there wearing them or sleeping at night.

Here is the stat block so far

Treasure Bug
Small Swarm of Tiny Insects, any alignment
Armor Class 14
Hit Points 18 (3d6)
Speed 30 ft.
STR DEX CON INT WIS CHA
8 (-1) 18 (+4) 10 (+0) 3 (-4) 6 (-2) 16 (+3)

Skills: Perception +0
Damage Vulnerabilities: lightning
Senses: blindsight 30 ft., passive Perception 10
Challenge 2 (450 XP)

—Abilities—
False Appearance:
While the treasure bug remains motionless, it is indistinguishable from treasure.
Swarm:
The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a key. The swarm can't regain hit points or gain temporary hit points.

—Actions—
Consume Flesh:
Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 2d6+4 damage.
Paralyzing Bite:
Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 1d4+4 damage. On hit, CON save DC 15 or be paralyzed at the end of the targets turn, after the first, they get another save.

[Bjarkmundur]

I'm not really good at balancing monsters, but I have some good resources in my signature to compare this to.

What you wrote looks more like a either a CR0,5-1. What's the XP budget for this ambush?

[SnowPlowMan]

What you wrote looks more like a either a CR0,5-1. What's the XP budget for this ambush?

No real budget. Just something to throw into loot to surprise with the party at all levels. I workshopped it with a friend and last second I changed it’s STR from 12 to 8 this might be the the reason for the CR being to high. I just couldn’t justify a swarm of bugs with a strong STR score.

[Bjarkmundur]

I can create this monster using any difficulty between 1/2 and 5. So i kinda need some way of deciding what the best numbers are based on your PC level, number of PCs and desired difficulty level.

It it's something that's just supposed to make one attack and then die, don't make an entire stat block. Just make a single attack, it's description and AC. Then you can just say it dies after one or two hits, based on how you want the random encounter to go. Like you said, it's not a dramatic fight, just a small encounter. There's no need for unnecessary details. If this is the case, have the paralysis an auto-succeed effect, since the creature is not likely to get a second chance to use the attack and the character is in no danger once paralyzed.

[SnowPlowMan]

If I had to put it into a category I planed to use it from 3rd - 7th level for group of 3-5 players.

I agree about the paralysis effect. The main advantage of the creature is about surprising the party. So it most likely will only get one good paralysis hit off. I didn’t mention it at the beginning, but I had planed for it to be an auto hit from the beginning. Seeing how it would pretend look more like jewelry then gold pieces, they would be worn directly on the body allowing them to auto hit. The stat block part of it is because my DM friends want the info for there future games.

[Nagog]

This looks like a great enemy to throw in to a Mimic Dungeon! Another great mimic flavor to throw in: Door Mimics! Floor Tile Mimics! And my personal favorite: ROOM MIMICS! (The whole room is a Mimic, inside the room is the inside of it's mouth. Makes for a great cinematic encounter!)

[firelistener]

Might this possibly be inspired by the treasure bugs from Delicious in Dungeon (Dungeon Meshi)? I loved the chapter in that manga with these things.

If you're aiming for CR2, I think it's good on the attacks and damage. I'd up the HP to at least 8d8, or the swarm is going to die extremely quickly. For reference, the Swarm of Insects in the Monster Manual has 22 (5d8) HP and is only CR1/2. Granted, the Swarm of Insects does slightly less damage and doesn't have the paralysis effect, but I think that DC15 Con isn't too terribly threatening. It's extremely rare for players to not have decent constitutions. I'd also give them the melee damage type resistance the swarm from the Monster Manual has. You can probably use that as your base and just beef it up a little. Be careful about using multiple of these though. Action economy will dictate that letting multiple of these loose on a party could be disastrous with the paralysis effect. It could very quickly shift the battle from being an even fight to being lopsided in favor of the bugs.

Sounds like a great monster to use!

[Bjarkmundur]

If I had to put it into a category I planed to use it from 3rd - 7th level for group of 3-5 players.

Well that makes a lot of sense. A monsters use is its main design goal. Since it's use is to get one good panic-inducing hit off before most of the players get to act I'd go for something along the lines of dealing no more than 15 damage on the special attack, since the average HP of a 3rd level adventurer is 23. That insures the hit will be panic inducing, without killing anyone outright. But then again you also get to choose who you target, so you can pretty much choose any damage number you choose. Writing down "3/4 of the target's remaining HP" is a bit silly, but it's still pretty accurate.

I would use the Ambusher theme from my monster math excel sheet. Their damage is designed to be 'front loaded' and they get their durability through some sort of 'untargetable' ability. This means an ambusher usually only attacks every other turn, and spends the rest of the time hiding (gargoyle, invisibility, phasing out, etc). To compensate for one turn of one turn of not attacking and being 'untargetable' we compensate by making it half as durable and twice as threatening.

AC: 10
HP: 12 (+6 per PC level above 3rd)
Swarm Resistances: ​Piercing, Bludgeoning and Slashing.
Attack: 4
Damage on hit: 15 (+8 per PC level above 3rd)
DC: 12
Save: 4
CR: 1 (+1 per character level above 3rd)

Paralysis attack is then a 'long rest' ability that deals roughly 3d6+4 damage (but for your encounter I'd just use averages without rolling dice) and paralyzes the target. If that sounds a tad strong you can say that the target is paralyzed for 1d4 rounds, then decide if you want to allow multiple saving throws or not.

It's at will damage can be far lower, just in case the bugs get to make another attack. There is precedent for a swarm doing less damage when damaged, on the account of most of the attackers within the swarm are dead. You can use that flavor to describe the suddenly reduced damage output of the swarm.

[SnowPlowMan]

Paralysis attack is then a 'long rest' ability that deals roughly 3d6+4 damage (but for your encounter I'd just use averages without rolling dice) and paralyzes the target. If that sounds a tad strong you can say that the target is paralyzed for 1d4 rounds, then decide if you want to allow multiple saving throws or not.

What if I just changed Paralyzing Bite to an ability with no damage but to an on hit effect with the DC at 12? It could also be a number of uses per day with a bit higher DC maybe 14.

[SnowPlowMan]

Might this possibly be inspired by the treasure bugs from Delicious in Dungeon (Dungeon Meshi)? I loved the chapter in that manga with these things.

It totally is.

[Bjarkmundur]

What if I just changed Paralyzing Bite to an ability with no damage but to an on hit effect with the DC at 12? It could also be a number of uses per day with a bit higher DC maybe 14.

I mean, you essentially are asking for two versions of this monster. One that fits your specific encounter, and one that fits repeated uses for another DM. There's no reason why you can't have the mechanics working behind the scenes different between the two versions, as long as its characteristics don't change. Any player who might encounter both versions won't be able to tell the difference, due to the short nature of your encounter.

For your version, deal a bunch of damage, make whatever save the player makes too low, and have it only work once and pick the duration that best serves the drama. You could even say that "Make a x saving throw or be paralyzed for the duration. On success, the target is instead stunned/incapacitated.", just to account for the possibility of the player making a REALLY high saving throw and feeling cheated it didn't resist the effect. Otherwise, just say it happens automatically, or that the monster rolled a crit or some other arbitrary mechanical reason for why the player can't resist the effect.
It's a thematic encounter meant to invoke a feeling in your players, not serve as an obstacle or meaningful encounter for the story as a whole.

I once ran a combat encounter where I had decided that the PCs would be overwhelmed by a tribe of natives using poison darts. I ran it as a full combat encounter, but success was never an option. My group's healer verbally beat the **** out of me and told me that "if you want something to happen, make it happen. Don't let me sit through a no-win scenario for 60 minutes!" . What I should've done was forgo all the mechanics, run one round of combat, and then say "Darts come flying out of their blowguns, and within seconds your vision fades to black. You wake up in...." Your's is a similar scenario. Do what you have to do to get the feeling across, and don't overthink it. For the players it's going to be a 10 minute ordeal, nothing more.

For the other DM's version, you have to be a bit more careful since you never know how many he's going to but into his encounters, and how much he's going to use that ability.
If it makes the attack every round it should deal 10 damage average (+5 per PC level above 3rd), instead of the 15+8, which is designed to make up for the fact that it only uses the attack every other round. For this 'general' version, the monster's HP should also be increased, 15HP (+7 per PC level), and have a measly save of 11 (+1 per PC level, maximum 14). This makes it in line with what the DMG expects in terms of calculating difficulty level, allowing him to pair it with any other monster and working with any encounter calculator he might be using.

This is the homebrewer's dilemma. Designing things for yourself to use at your own table is a completely different world from designing things for others to use. Besides, whatever you design you know like the back of your hand, meaning its easy for you to make adjustments on the fly. When designing content for others to use you have to meet the standards they are used to, and minimize the amount of adjustments they could make. It's tough, but most of us welcome the challenge (and then use something completely different in our own games).

The numbers are arbitrary for your version of the monster. Story and feeling should always come first. Especially when there's no conflict. I mean, the adventurer's are always going to win, why make it seem otherwise? It's a scene in a movie, but you know it's the middle of the movie, so it's not really going the be the thing that ends the entire story-line. That still doesn't mean you can't use it to build atmosphere or introduce new creatures to your world. Just don't make the mistake of thinking it's more important than it is, that's how you get to overthinking.

[J-H]

http://blogofholding.com/?p=7338#together

For a CR 2 monster, its HP are about right since it probably has resistance to weapon damage as a swarm.
Its DC is very high - where do you get 15 from? A 3HD monster would normally have a DC of 8 + 2 Proficiency + STAT, and I would expect the strength of the paralysis to be based on CON (+0). DC10 will still be failed 40% of the time by most characters.

I'm assuming it can only make one attack per round, and has to choose which one to make.
Keep in mind that a paralyzed creature will automatically get critted, so if they fail their 2nd save, the target is going to take an average of 27 damage.

[SnowPlowMan]

Bjarkmundur your help and advice is more then I could have asked for thank you.

[Bjarkmundur]

Bjarkmundur your help and advice is more then I could have asked for thank you.

Thank you! I was getting afraid I was coming off as aggressive and... mean, which was not my intention <3

Whenever you are creating monsters, go check my resources (see sig). I use it every time I create a monster, it's SO useful ^^