Postmortem on the Autophage Battle

I was pretty happy with how last night's battle went, I wanted to challenge the Chain, I didn't want it to feel like an 'Epic Boss Battle' with creatures that have legendary actions. I just wanted to pick a relatively-low CR monster that had maybe one cool special ability, and challenge the heroes by just outnumbering them. 

It worked well I thought without me having to do any tweaking during the battle, and I figured that would be a good opportunity for a deep-dive into what I did.

The heroes fought 8 "autophage" homunculi; a virus-like worm colony that takes the shape of a man and can infect its victims.

I used the Spawn of Kyuss from Mordenkainen's Tome of Foes, an undead monster that originally appeared in the 1981 Fiend Folio as the Son of Kyuss.

When selecting the monster , I just wanted something that could work as a kind of self-replicating enemy that "infected" people and would be dangerous to allow out of Ringwell and the Spawn of Kyuss was perfect. 

I decided 8 of these CR 5 creatures would be a good challenge. The Chain of Acheron are pretty tough, they've accumulated some dope magic items and the game sort of assumes magic items are optional, so if you give your PCs a lot of cool magic, you need to up the ante on the encounter design. CR 5, not a big deal for a party of six 7th level heroes. But EIGHT of them means if the players aren't careful, things could go south without warning.

The trick to challenging PCs in 5E is the action-economy. If your monsters are taking fewer actions each round than the heroes, the monsters will lose. Once the monsters are taking MORE actions than the heroes, then you really start pushing the PCs.

I didn't change their AC or HP, or even their (not very high) attack bonus. I changed their type so they weren't Undead. That was a big deal, because the heroes have a lot of powerful tools to deal with undead. But also, these are not undead! I didn't change that type to thwart the heroes, I changed it purely to fit the narrative.

Because they aren't undead, I changed their bonus damage from necrotic to poison. No big deal.

I boosted the save from their worm attack. Here's something; I don't know what I boosted it to. I don't mean I forgot, I mean I never decided. I just knew a DC of 11 was "too low." I know 14 would have been "too high" so I knew it was either 12 or 13 and I'd pin it down once someone rolled a 12 or a 13.

This ambiguity in the encounter design is a powerful tool. Let's say, the first three heroes to make saves vs this ability all rolled 15s or above. Well, that means the encounter has opened with a low degree of drama. "These worm things, not a big deal."

Had that happened, and the next player rolled a 12, I probably would have decided the DC was 13. Because I want to create drama. But also, I want a fun, engaging encounter! The two are closely related.

Conversely if the first three players had all rolled 7s on their saves, and the next player rolled a 13, I probably would have decided the DC was 12. "I've already infected three PCs, let's give them a break."

Keep in mind, I'm not changing the DC in the middle of the battle. I would consider that incredibly poor sportsmanship. I just knew 11 was too low, and 14 was too high, and I waited to see how the battle went before I decided any further.

I believe that worked.

Because they weren't undead and were therefore less vulnerable than an actual Spawn of Kyuss, and because their save DC was higher, I deleted their regeneration ability. I don't mind regeneration in solo monsters, but keeping tracking of regeneration for 8 monsters is more bookkeeping than I want to do.

As I often do, I allowed the monsters to get into position. The Autophage homunculi "appear" or grow from motes into worms into colonies of worms in seconds and this means I can put them pretty much wherever I want.

That's super important. If it had just been a corridor full of PCs and a room full of monsters, the battle would have been over in a round. But by opening the encounter with the monsters "in amongst" the heroes I drastically increased the difficulty. Just that setup made the encounter wildly more challenging and interesting.

I just need to make sure there's a plausible reason WHY the monsters start in those positions. The idea of these creatures starting as an airborne contagion is important, not just to that setup, but to the overall threat of the Autophage, which is not over.

Because of the context and description, the players accepted that these things would be able to appear in the positions they did.

The result was an encounter with a very low "tipping point." The tipping point is that moment in an encounter where the trend toward loss or victory changes. The lower the tipping point, the more likely such a change is. In this encounter, it was the Worms that lowered that tipping point.

The worms require high Dex to avoid, which the Chain does not have. The worms take an action to remove, which completely fucks the Chain's action economy. Simple solution, totally plausible ("it takes an action to remove a worm") but it totally transforms their ability to fight.

And the worms' effect is cumulative. You can have several worms in you, each doing 2d6 damage. 

Finally, the worm effect is very 4E which is good design. It's not "a roll and an effect," it's three discreet stages. 

1: Roll or get a worm.

2: Spend an action or the worm burrows

3: cure disease or you are going to die. :D

That's fantastic. And it almost caused the party to fail. Retreat, or wipe. But in a critical moment, King withdrew to range, and fireballed the entire party and the Autophage, using his Zeal Cleric channel divinity to enhance the damage.

Seeing how effective that was, and already in position, Copper did the same thing with his fireball arrow and that effectively turned the encounter from "we might not make it" to "we're going to win" and that kind of decision making "guess I have to fireball my teammates" is dramatic and tactically satisfying. Because it worked!

But the encounter wasn't over, the heroes still had to deal with the worms inside them. 

This is another classic Matt Colville "I have no idea how the players are going to get out of this" encounter. I knew the worms could be cured by anything that curses disease OR curses. I knew the players had access to those spells, but I had no idea if they had prepared them.

And I didn't know if they'd even bother to figure it out. They didn't, really, they never made a check to determine "can we figure out how to stop the worms inside us?" They just sort of brute-forced their way through it. 

They eventually poured over their spells and DISCOVERED that lesser restoration cures diseases. Great, that will work. They never guessed/figured out that uncursing also works.

Lars didn't know that's what lesser restoration did and asked if he could retcon his spell choices under the entirely reasonable premise that King knows what they do. I 100% agree and never for a second doubted that Lars was being sincere and not trying to game the system.

I am not a fan of punishing characters for their players' ignorance. :D

So they had enough spell slots that between the Illrigger and the Cleric, they could fix everyone. If they had retreated into the city in order to get help, they would have released the Autophage into Capital and caused a major epidemic.

Happily, OD thought of capturing one of the live worms and keeping it in a flask so not only does that opportunity still exist, the players now have a very powerful weapon. They discussed, after the stream, taking the autophage sample to the Crysopolis and dropping it on Ajax's floating city which I think is exactly how they SHOULD be thinking.

More dangerous creatures weapons and lore await....