345 Modifying Encounters on the Fly

Oh, yeah. Still getting a handle on 5e. First round, the antagonist attacks. My first thought, “Oh, god…they’re all going to die. What the crap can I do?”

The first thing I did was consider the setting and consequences of the attack.
They were on a ferry being pulled across a river. The antagonist was awaiting their approach and had unleashed a Fireball. The PCs were half down, half barely alive. So…“The fireball burned the tether rope for the ferry. You’re now drifting rapidly downstream. The Warlock on the shore yells in frustration and sends minions to pursue you down the shoreline of the river, but they have to go around rough and overgrown terrain. You have a bit of time…”

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Now y’all are just messing with me. I distinctly heard someone (assuming it was @Fafhrd) pop the top on a can during this episode. Even though it was only 10:30 in the morning I nearly had to go to the fridge for a beer.

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That was @Sean - he was drinking one of those fruit summer beer things.


LOL. Yuck. :slight_smile: I went to the AM/PM the other day and outside was a table set up to shill some energy drink called Bang 5. Next to the table (of course) was an attractive blond in a fluorescent tank-tini. My friend was with me and I said - “Bang 5? I’m 53 and overweight. I’d be lucky if I could Bang 1.” I thought it was pretty funny.


that is pretty funny :rofl:

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As a general rule, I never adjust a combat encounter’s stats on the fly, even if what was supposed to be a tough encounter becomes a cake walk. If that does happen, I try to find a way to complicate the scene by calling in reinforcements or using a fireball spell to set the room on fire and ramp up the tension. But almost never by adjusting the details already prepped and recorded.

Back in my 3e home brew campaign, I wanted to pit the PCs against a massive horde of flesh-eating zombies. The idea was that they had to survive the night as these zombies would turn to dust at dawn. It was designed to force the PCs out of their standard fight-in-the-open approach and add some mobility to the encounter as they had to move from one secure shelter to another to outlast the night.

Uh, yeah, that’s not what happened. The sorcerer had just learned a polymorph spell that would allow him and two others to turn into a creature they encounter before. So in their waning hours before the horde attacked, they chose a large insectoid creature called a “roo-ken-eer” from the previous adventure and decided to hold out for as long as possible in (sigh) a big fight out in the open. Well, that choice of monster just happened to provide the PCs will the PERFECT immunities and damage reduction that allowed them to survive hundreds of zombies attacking as a horde AND it also gave them the ideal attack that would allow them to sweep through the horde. Once I realized they had (by sheer luck) picked the perfect defence and therefore nerfed all my plans… I gave it to them. They planned, took what they knew about the situation, and made all the right choices to win the battle. In that moment, they deserved the complete victory.


…in the next adventure, they had to go up against a pit fiend. They were something like a CR10 party or something. I needed to take something from them and wanted to make sure it would get done. So I took the main boss for the whole campaign and brought him in for an early appearance. No deaths, no injuries, just some dislocated jaws as they saw a pit fiend take the sorcerer’s younger brother into a portal to Hell. They were not wearing brown pants that day, let me tell ya.

So maybe I do adjust things… but later. Once they’ve proven themselves capable of kicking ass in a tough encounter before the final act of the game, standard pacing and plot devices tell us to bring them down a notch as their nemesis tries to quell this growing threat. You blow up the Death Star, the Empire’s gonna crush you with giant metal camels.

And this DM don’t fuck around when you wipe out his zombie horde.


So… we’re just talkin’ how far in advance we each adjust things. :slight_smile:

For some of us, it’s before the next combat round, others before the encounter ends (such as unexpected reinforcements) or between encounters…


If you’re not adjusting things you might as well just be playing an MMO. One of the greatest strengths of being a GM is that you’re the director of the action. If something gets too boring you can tweak so it becomes less boring. If a fight gets too intense you have the ability to make the villain make a fatal mistake!


I adjust things on the fly all the time. I always have an eye towards whether I accidentally built a death trap. That doesn’t happen often though. And I’ll make changes to keep things interesting but if the players drop a major bomb on me or a crit cripples my major foes, oh well! I never want to take that away from my players and I let them enjoy the edge.

I typically build my BBEG encounters to work in phases so an alpha strike can be enjoyed but doesn’t ruin a climactic scene. That’s a little trick I picked up from 13th Age and it has served me well.

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I’m a bit baffled by the question, honestly.

Assuming that a GM creates the encounter in the first place - they are already making mechanical “modifications” to the adventure. Foes will be selected/created/skinned and then further “modified” in various ways, including stats, environmental factors, props/magic items, traps, etc…

Who hasn’t said "My very experienced players already know how 5e MM Trolls work, so to challenge them, I’m gonna [change their vulnerability or declare limbs act after being severed or…]?

What’s wrong with making that same decision just after the encounter actually begins? Or after another encounter that was too easy? Or whenever?

Or, is this all about published adventures and players wanting to have fore-knowledge about the way to defeat every encounter [aka full spoilers]?

If so, my response is: I am not an MMO simulator.

Its not about pre-published adventures or about changing a trolls stats before a session starts.

The question (as the originator of the question) comes from me feeling uneasy (and No I am not new to running games) when I modify things on the fly. I am not talking about oh they went THAT way…crap…nothing planned for that ok here is “something”. Its more this monster that they are fighting has 100 HP and after 1 surprise round it has 10 HP left AND the players win initiative. The thing is clearly going to die now without much drama (story). The question basically asked how the BS community felt about maybe tossing some extra HP on it (simple solution as Brett implied), extra minions, an environmental condition not previously planned, etc.

Its like kicking a ball out from behind a tree while golfing to give yourself a better shot. Some people would say your cheating the game while others would say no big deal- we are not pros - have fun.

I expected differing opinions on the topic and was curious how others felt.


Thanks for the clarification - as often happens there has been some topic drift. :slight_smile:

Can you speak to the unease you feel? If you assume you are the only one that knows how many HP this creature has, why worry about bumping it? Your golf example implies that this would be somehow “cheating”. My question is “cheating what?”

I’ve seen DMs on both sides of that question. I know a couple who won’t change an encounter no matter what. That’s just what they are comfortable with. As I mentioned, I am firmly in the GM camp who will modify encounters to suit my purposes, even on the fly while the encounter is in progress. There are certainly pros and cons to both approaches though.

The static (for lack of a better term) GM just runs the encounter as is, lets the dice drive the narrative, and adapts the story as that happens. I’ve do that a lot, especially in encounters where it is not as important to hit a certain story beat. My players did this too me last week. They went up against an adult blue dragon (D&D 5E). A couple of smart spells and some incredible die rolls and the dragon was dead in the second round. I RPed the dragon’s frustrations as it’s well planned lair defenses fell apart and it’s overconfidence in it’s abilities got the best of it. I thought about modifying it but the encounter wasn’t a boss fight or anything. It was just one story beat on the way towards the BBEG and more important minions. So I changed nothing.

On the other hand, I’ve run fights where I’ve modified on the fly to keep up with the players. I’ve added environmental effects. I’ve added hit points (although I agree, that can be a lazy approach sometimes). I’ve given important enemies alternate forms they transform into.

And in hindsight, I’ve had fights where I didn’t modify anything but wish I did. When we finished Curse of Strahd, the battle with Strahd went far differently than I planned. Of course, my players had spells in their repreatoire they had never used before because they knew Strahd was watching them and wanted to surprise him. Likewise, they surprised me with tactics they had never used before. Strahd didn’t go down easily, but he definitely went down more easily than I anticipated. Later on, I brainstormed on how to improve the encounter (which led to me adopting some tools from games like 13th Age). On the flipside, my players still talk about how they got the best of Strahd to this day. So overall, the encounter was a success.

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I have, I kid you not, played with people who proclaimed and demanded that all adventures be run as written so they would know that they defeated/completed the adventure. “How do we know if we did that if the GM modified or changed things? That’s not a fair way to challenge players.”

These players got PISSED when they found the GM changed something in the adventure. “Well, we’ll have to play this again how it was supposed to be played so we really know if it’s any good or not and if we can or can’t get through it.”

Strangest group I’ve ever played with.


I have experienced the same woth players in some instances with players.

@OldSchoolDM I couldn’t say why I feel uneasy about it. Like I am cheating the game or something? Would my players be happy knowing I did this? Do they care? I know some might. I am also the guy who sits at the red light at midnight that seems obnoxiously long with no traffic in sight. :slight_smile:

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On the other end of the spectrum, I just had a new player leave the game because I mentioned in passing that, “Sometimes I’ll incorporate a pre-written scenario (or parts of one) if I’m short on time, something unexpected comes up, or it’s a particularly good fit for something I need.”

He told me after the first session that I was a good DM, but since I said I’ll sometimes use pre-written adventures that he couldn’t play in my game. This was because now he could “see through the ‘veil’ of the story” and so the campaign didn’t work for him anymore.

The really ironic part of this was that I only mentioned it because the first session he was in involved elements from a pre-written adventure. Why did I use a pre-written adventure? Because this player let me know 20 minutes before the start of the session that he’d decided to run a Human instead of a Dragonborn, and a Volstrucker Agent instead of a member of the Cobalt Soul (Wildemount campaign.) My entire “get the new character into the game” scenario had been designed heavily around the fact that he was a Dragonborn member of the Cobalt Soul. That scenario was unsalvageable. So, with 15 minutes to go…yeah, I went with a pre-written scenario in order to buy time to re-work his introduction.

Some players can be very frustrating. (Of course, don’t get me started on frustrating GMs, either.)

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This looks like asking for a Unicorn to me. :unicorn:

I personally don’t believe it is possible, much less truly desirable.

I’ve never seen it done, even in organized play.

I’ve never been able to achieve this. Time alone thwarts all modules. :mantelpiece_clock:

I mean, I can kinda get that personal challenge for post-pre-published adventures. Even though I barely run my own stuff as written, playing the adventure as written (AAW?) and surviving can be a bonus goal. Especially if you want to say you survived the Tomb of Horrors as written.

That’s funny. :laughing: Have you tried to run ToH or played in it? In my experience, of all the original adventures, that’s by far the sloppiest/squishiest in terms of “run as written” -every single run has been subject to massive rulings work even before you get through the first real door.

The run I played in was blast, but I’m under no delusion that it wasn’t riddled with DM Rulings in every single encounter.

For example (spoiler) there is a cursed magic item that says to reverse the effects of a wish spell. Yeah. 100% on the fly DM dependent interpretation.

I think it’s great to share an experience like that with other groups, but in the case of Tomb of Horrors, I most often hear the stories of how the party died spectacularly! If I ever hear someone say: “Yeah. We beat ToH first try no problem” - that’s when I’d give them the side-eye! :stuck_out_tongue_winking_eye:

Meepo Forever!


Lol, this sounds like something a fedora tipping neckbeard would say. RPG’s truly attract some wacky characters.

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