D&D 5E King (for a day) of the Monsters: Rot Grub Swarm

[Elon Tusk]

My players had prisoners who escaped from them set a trap that included the body of one of the former players hanging from a tree. There was a hidden spiked pit in front of the body, but the players Perceived it. However, the prisoners placed a swarm of rot grubs inside the hanging body.

One of the players cut down the body, a wizard decided to pick it up to bury it. The grubs attacked the wizard with a crit. I rolled a 4 (on a 1d4) to determine how grubs entered the PC's body. Most other PCs didn't notice. A paladin cast cure wounds which didn't do anything since the grubs don't do damage until the start of the victim's turn. The grubs did 11 damage just before the wizard stabbed at one in his arm - I allowed it (seeing how this was escalating beyond my intentions), making him roll to hit and take 6 damage from his dagger while killing 1 internal grub.

Long story short, next turn a player cast Thunderwave, killing external grubs but really hurting wizard. Wizard then stabbed himself again and fell to 0 hp which means he "[FONT=&quot]dies as the rot grubs burrow into [his] heart and [/FONT][FONT=&quot]kill [/FONT][FONT=&quot][him]."[/FONT]

[FONT=&quot]The thunderwaver went to go claim the paladin's possession, had 3 grubs burrowed into his arm so he stabbed himself to kill one and then next turn cut off his own arm after remembering what happened to the wizard.[/FONT]

The party is at 4th and 5th level, heading toward the Tomb of Annihilation and one died (never to be resurrected) and another lost his arm all because of CR 1/2 rot grubs. They had no idea what to do to kill the grubs or that the grubs would kill them so quickly.

Thankfully, they then avoided the sack of gold left in their path that was actually a Bag or Holding with 12 zombies inside.

Has anyone else used rot grubs in their campaign?
Do they really seem like CR 1/2 creatures?

 

[The Scythian]

Mechanically, rot grubs are really easy to deal with. They're slow as molasses, they don't have a lot of hit points, and they can't sense enemies more than 10 feet away. They have one heck of an attack, but it's easily neutralized by fire or by a paladin's special ability.

With that being said, I think I would have handled things differently. Instead of allowing the paladin to waste an action doing something that would have no effect whatsoever, I would have pointed out that the wizard hadn't taken any damage from the grubs yet and that cure wounds wouldn't kill them.

Taking on twelve zombies trying to climb out of an opening that's two feet in diameter sounds like a cakewalk, honestly, but how do you fit them all into a space that's four feet on a side and can only hold 500 pounds?

 

[Elon Tusk]

Mechanically, rot grubs are really easy to deal with. They're slow as molasses, they don't have a lot of hit points, and they can't sense enemies more than 10 feet away. They have one heck of an attack, but it's easily neutralized by fire or by a paladin's special ability.

With that being said, I think I would have handled things differently. Instead of allowing the paladin to waste an action doing something that wouldn't have no effect whatsoever, I would have pointed out that the wizard hadn't taken any damage from the grubs yet and that cure wounds wouldn't kill them.

Taking on twelve zombies trying to climb out of an opening that's two feet in diameter sounds like a cakewalk, honestly, but how do you fit them all into a space that's four feet on a side and can only hold 500 pounds?

Rot grubs have 5' speed, but used as a trap they had 10' blindsight and surprise and rolled a crit and were inside the PC before he could act.
Once inside only fire by the end of the target's next turn or a spell that removes diseases has any effect; the players didn't know or think of either of those in the < 3 rounds they had.

It's not my style of DMing to remind players of how best to use their abilities. I like it when they role-play giving each other advice. I expect them to run their 1 player while I run all the NPCs.

Yeah, and I totally miscalculated the Bag.

 

[Raith5]

"My players had prisoners who escaped from them set a trap that included the body of one of the former players hanging from a tree".

Man, that is a dark entry to a post! Why didnt the grubs consume the body, do they only eat living flesh?

 

[Elon Tusk]

"My players had prisoners who escaped from them set a trap that included the body of one of the former players hanging from a tree".

Man, that is a dark entry to a post! Why didnt the grubs consume the body, do they only eat living flesh?

The players agreed to return grung prisoners through the jungle to the grung village as a means of negotiating, but the prisoners escaped and set a trap.

The grubs attacked when the dead bodies they were in were moved.

 

[The Scythian]

Rot grubs have 5' speed, but used as a trap they had 10' blindsight and surprise and rolled a crit and were inside the PC before he could act.
Once inside only fire by the end of the target's next turn or a spell that removes diseases has any effect; the players didn't know or think of either of those in the < 3 rounds they had.

My point was that, in terms of raw statistics, the rot grub swarm is extremely weak.

Your rot grub swarm was set up in a way that nullified its disadvantages and it also got a series of lucky breaks--it got surprise, hit with its attack while it had surprise, got the best result it could have gotten with that hit, had a character who could have easily solved the problem waste a round, and then had another character cast an offensive spell that actually helped the rot grubs kill the wizard.

The characters in your group certainly had the resources to kill the rot grub swarm and neutralize its effects several times over, which is ultimately what challenge rating is all about.

It's not my style of DMing to remind players of how best to use their abilities. I like it when they role-play giving each other advice. I expect them to run their 1 player while I run all the NPCs.

It's not my style of DMing, either.

However, I recognize that I am the primary interface between my players and their characters, as well as the world they inhabit and the challenges they face. I am the window they rely on for an accurate picture of what's going on. If a player says they want their paladin to cast cure wounds on an unwounded character, I think it's fair to clarify that the character they're casting the spell on isn't actually wounded. If a player hopes to kill burrowing parasites with a spell that can never kill burrowing parasites, I think it's reasonable to clarify what the limits of that spell actually are, on the grounds that while the player may not understand the spells capabilities, the character casting it certainly would.

 

[Elon Tusk]

My point was that, in terms of raw statistics, the rot grub swarm is extremely weak.

Your rot grub swarm was set up in a way that nullified its disadvantages and it also got a series of lucky breaks--it got surprise, hit with its attack while it had surprise, got the best result it could have gotten with that hit, had a character who could have easily solved the problem waste a round, and then had another character cast an offensive spell that actually helped the rot grubs kill the wizard.

The characters in your group certainly had the resources to kill the rot grub swarm and neutralize its effects several times over, which is ultimately what challenge rating is all about.



It's not my style of DMing, either.

However, I recognize that I am the primary interface between my players and their characters, as well as the world they inhabit and the challenges they face. I am the window they rely on for an accurate picture of what's going on. If a player says they want their paladin to cast cure wounds on an unwounded character, I think it's fair to clarify that the character they're casting the spell on isn't actually wounded. If a player hopes to kill burrowing parasites with a spell that can never kill burrowing parasites, I think it's reasonable to clarify what the limits of that spell actually are, on the grounds that while the player may not understand the spells capabilities, the character casting it certainly would.

Yes, unluckiness and a lack of tactics amped up the potency of the grubs, but the grubs still kill quickly. Even if the players knew what it took to kill them, doesn't mean they'd have immediate access to fire or the restorative spells required.

The weird thing about the grubs (maybe a design flaw) is that they attack with a bite that allows them to burrow into a creature, but the creature doesn't take damage from the bite or burrowing until the start of their turn. The grubs are "finger-sized maggots" - seems like biting and burrowing would cause immediate damage. The paladin saw the bite and burrow, tried to heal that, but RAW says their is no damage yet to heal since the wizard's turn came after his.

 

[The Scythian]

Yes, unluckiness and a lack of tactics amped up the potency of the grubs, but the grubs still kill quickly. Even if the players knew what it took to kill them, doesn't mean they'd have immediate access to fire or the restorative spells required.

The weird thing about the grubs (maybe a design flaw) is that they attack with a bite that allows them to burrow into a creature, but the creature doesn't take damage from the bite or burrowing until the start of their turn. The grubs are "finger-sized maggots" - seems like biting and burrowing would cause immediate damage. The paladin saw the bite and burrow, tried to heal that, but RAW says their is no damage yet to heal since the wizard's turn came after his.

The delayed damage isn't a design flaw. It's an attempt to make combat with the rot grub swarm less dangerous, as it will often (but not always) result in one or more characters getting the chance to act before the target takes any damage at all. In the case you presented, the problem wasn't the delayed damage tricking the paladin into wasting an action, it was that you didn't say something like, "You can cast cure wounds, but while the rot grubs are burrowing into the wizard's flesh, they haven't actually done any meaningful damage yet." That would have given the paladin's player a more accurate idea of what was going on in the game world. It's not the monster designer's fault that you didn't do that.

Beyond that, the rot grub swarm is certainly a tough CR 1/2 monster, but most encounters with it will be a cakewalk. Its attack bonus and AC are awful, its hit points are low, it's slow, it has very limited senses, and it must move into an opponent's space to target it. They're not exactly the stealthiest creatures, either. Most of the time, even low-level parties encountering rot grubs are going to walk away either completely unscathed or with very little damage. Sometimes, one or more party members will die, but if you're not playing Tomb of Annihilation, that's not necessarily a big deal.

Since you are playing it, one thing you might consider is treating monsters capable of outright killing characters, instead of merely downing them, as significantly more dangerous than their challenge ratings might otherwise indicate.

 

[Elon Tusk]

The delayed damage isn't a design flaw. It's an attempt to make combat with the rot grub swarm less dangerous, as it will often (but not always) result in one or more characters getting the chance to act before the target takes any damage at all. In the case you presented, the problem wasn't the delayed damage tricking the paladin into wasting an action, it was that you didn't say something like, "You can cast cure wounds, but while the rot grubs are burrowing into the wizard's flesh, they haven't actually done any meaningful damage yet." That would have given the paladin's player a more accurate idea of what was going on in the game world. It's not the monster designer's fault that you didn't do that.

Beyond that, the rot grub swarm is certainly a tough CR 1/2 monster, but most encounters with it will be a cakewalk. Its attack bonus and AC are awful, its hit points are low, it's slow, it has very limited senses, and it must move into an opponent's space to target it. They're not exactly the stealthiest creatures, either. Most of the time, even low-level parties encountering rot grubs are going to walk away either completely unscathed or with very little damage. Sometimes, one or more party members will die, but if you're not playing Tomb of Annihilation, that's not necessarily a big deal.

Since you are playing it, one thing you might consider is treating monsters capable of outright killing characters, instead of merely downing them, as significantly more dangerous than their challenge ratings might otherwise indicate.

Sorry, that's ridiculous. Four finger-sized maggots burrowing under someone skin "haven't actually done any meaningful damage yet" doesn't make sense. The problem wasn't mine as a DM for not reminding one player that I hadn't told another player to deduct hit points.

Sure they're slow, defenseless (outside a body), limited in senses, etc. That's why they don't make much sense just putting them out in the open where they can be avoided. The only use I see for them is having them hidden or on/near something the players want/need.

A 3rd level Revivify brings the dead character back with 1 hp, but the grubs are still alive in its heart eating away.
A 5th level Reincarnate is a kind of big deal as it permanently changes the PC.
Resurrection works great, but it's a 7th level spell.

I'm not sure why you are telling me to treat them as higher level CR; I used the 1/2 CR rot grubs against a party of five 5th level players.

 

[GMMichael]

One of the players cut down the body, a wizard decided to pick it up to bury it. The grubs attacked the wizard with a crit. I rolled a 4 (on a 1d4) to determine how grubs entered the PC's body. Most other PCs didn't notice. A paladin cast cure wounds which didn't do anything since the grubs don't do damage until the start of the victim's turn. The grubs did 11 damage just before the wizard stabbed at one in his arm - I allowed it (seeing how this was escalating beyond my intentions), making him roll to hit and take 6 damage from his dagger while killing 1 internal grub.

Long story short, next turn a player cast Thunderwave, killing external grubs but really hurting wizard. Wizard then stabbed himself again and fell to 0 hp which means he "[FONT="]dies as the rot grubs burrow into [his] heart and [/FONT][/COLOR][COLOR=#454543][FONT="]kill [/FONT][FONT="][him]."[/FONT]

[FONT=&quot]The thunderwaver went to go claim the paladin's possession, had 3 grubs burrowed into his arm so he stabbed himself to kill one and then next turn cut off his own arm after remembering what happened to the wizard.[/FONT]

Sooo...a rot grub chewing through a character's skin and then crawling under the skin isn't considered damage? At least, not until the victim's turn?

But stabbing a rot grub (that's under your skin) does more damage to you, even though it's the rot grub you're stabbing, than the grub does during its first turn?

And then, having witnessed this, another character decides to play with the rot grub hotel?

So he promptly gets three grubs of his own to worry about. But rather than stab the big, ugly, not-immediately-damaging bumps under his skin, he opts to cut off his own arm...in just one round?

The rot grubs are not the problem here.