Dungeons and Dragons

You really can't fix it by artificially nerffing because assuming that the platform has random enough dice (which is most likely does for any real needs) the fact that they have thrown poorly before doesn't mean that they will do so after your changes.

I don't know how you are keeping track of the rolls but if you aren't, I would first try that to truly see if it really is the case that the rolls are lower than average. Our memories of things going poorly aren't objective and tend to enlarge amount of bad outcomes.

Use digital dice?

Narrative solution would be to reveal the party has been cursed somehow this entire time. You can then give them a trinket/spell that mitigates low rolls. They get the best of 2 rolls once per combat or something like that.

You could borrow hero points from Pathfinder. Basically, each player gets one or two hero points at the beginning of the session and can spend it to reroll a d20 at any point in the night. You take the rerolled result. Note that these expire at the end of the session and cannot be stacked up for next time.

Probability is just probability. What separates D&D from a video game is the flexibility of the players and the DM. Lateral thinking wins the day!

My advice? Review your players' backstories and add in an unexpected ally who shows up just in time to deliver the solution, but at the cost of needing their help with something conveniently related to the main quest. Alternatively, encounter an NPC who, likewise, conveniently assists them out of a sticky spot in exchange for pursuing the main quest.

I have a rule as DM that I will never fudge rolls against the players, but I will fudge rolls in their favor if it fits the narrative. Three players consecutively miss an enemy? Oh no, next turn it got a critical fail and then failed a Dex save, slipping and landing prone. I guess the players get advantage on melee attacks! Don't do this often, but I'm the right spot it's fine.

Monsters can just be dumb, too. INT of 6 means those Blobby Blobs are gonna fight poorly, attacking the tank and splitting up attacks. Also, the players don't know your monsters' stats, so you can make an attack that would get it to 1 HP instead kill an enemy. I also don't do this often, but sometimes they just get unlucky, and no reason to TPK.

Speaking of TPK, you can let them fail forward. Monsters rarely have reason to attack downed/unconscious PCs, so let them roll death saves, but it usually takes a while to die. Everyone's unconscious? Stop combat, no more death saves. Instead, they wake up as prisoners and have to escape. I had a particularly fun one where my players would have died to a trio of night hags (if you've played Curse of Strahd, you know the ones). Instead, they woke up and were given a mission, but the bags also stole parts of their "souls," taking Max HP from one player, speed from another, giving one a trait that they would lose all hope, stealing another's eye (disadvantage on Perception), etc. Then they had to fulfill the mission, but later came back at a higher level and beat the hags, gaining their souls back. Everyone loved getting revenge!

I'm partial to semi-narrative combat. My baddies rarely fight to the death, so they'll disengage and run away when they take too much damage or we start to get bored. Could you try something like that?

Nerfing the CR doesn't seem terrible, so long as you have a backup plan in case they roll well.

Another option might be using Inspiration or another meta-currency to allow the PCs to push a near miss up to a hit. I'm playing Cyberpunk RED right now, and it has Luck, which kinda does that.

Alternatively, you could try to design fights with non-murder win conditions. Like the PCs are just trying to get across a bridge, etc.

They need to roll the d20 and not the d12.

But seriously, the party can figure out AC, but not hit points. If something is dragging on, just have things die on the next hit. I know some people would complain about it, but it is the group's game, if something isn't fun, change it. You have the power.

Also, some things fight to the death, but it is also ok to have some things surrender or run away. Fighting a group of bandits? When one goes down, have someone scream "Bear! No!" and run away crying. Killed half the goblins? The rest turn tail and run.

There are many levers to pull, and don't be afraid to use them.

Tell them to roll real dice for attacks and trust them to not lie.

Can you have everyone roll a 50d100?

I'm curious if there's a technical issue at play that's influencing the random number generator. Such as a script blocker or privacy tool. There should be no discernible pattern between the players.

There's also the phenomenon that true random doesn't feel random. Such as when a music player feels like it's shuffling between the same 20 songs instead of the whole list.

Why would a fix be required? It seems like you expect the bad rolls to continue.

Go for a tpk.

Then, once they die, have them wake up with slave bonds and have to complete 3 trials for their subdemon overlord in order to be freed.

During that time, get a DM screen and hide your rolls from them so you can fudge a little to make the game more fun.

The luck system might be something to look into. It can help mitigate consecutive failures while maintaining balance.

You could try attacking with hordes of low CR enemies instead of a few high CR ones.

My recent game has been similar. Not because I roll badly, but because the GM is incapable of rolling below a 16.

And I say: if they die, they die. You're playing digital, you're not going to run out of character sheets.

Give them custom weapons or spells that are most effective when you roll low.

Players not succeeding on rolls isn't necessarily a bad thing. It can increase tension in your encounters and is ultimately something you can't control directly. You can fudge dice on your end, but honestly this reduces tension and if you're not decisive about it can be pretty noticable.

So what can you affect? First, the stats of the monsters you're throwing against them or the DCs that you're looking for can be adjusted. If they're consistently struggling more than is enjoyable, you can always scale things back a bit when you're prepping encounters. Inspiration can also be a great way to let the players swing things in their favor without feeling like they're being handed a success. There are also times when you can throw in a "oh actually, roll that with advantage" with some reasonable excuse, which also doesn't feel like a gimme. But aside from this you have a whole toolkit in your ability to shape the world around them.

Magic items can be really helpful here. A staff with silvery barbs or bless or something similar can be a great way to put some die manipulation into your players' hands, especially if the party composition lacks things like this. But don't forget that you can also use set pieces.

Maybe the ceiling above an enemy has a weak point, or they're standing directly under a chandelier or some nets. Maybe an enemy prefers their own safety in a crowded fight over that of their allies and drops an AOE that brings some friendly fire. Maybe some magic item or wards on the monster are responsible for part of its AC and dispelling it might help. The options are only limited to what you can imagine.

For great tension in a game, though, you want there to be risk of failure. Resist the urge to just hand the win to your players. Your job isn't to make sure they win every encounter, that's their job. They'll sort it out themselves. Maybe they don't, though, and they're taken alive. Maybe the entire party wipes and properly dies, but in 100 years someone enters their tomb and ressurrects them to perform some task that they're uniquely suited for. Maybe some sketchy wizard who wants something from them and has been scrying on them for the past week teleports them away, only to back them into a corner and try to make them do something against their interests or beliefs. Maybe they're captured and lose this particular fight, but are able to rest wherever they're being held and find others to help them secure their belongings and fight back.

In general, don't worry about how the dice are rolling. They're meant to be out of your control, but you can do literally anything with the world.

If its me and I need them to push through something like this they befriend an NPC that is either powerful enough to carry them through combat or gives them an artificial buff to hit rolls or something, like a baby dragon they gain focus from because they have yo protect him or a mischievous imp that sings silly ballads that inspire them. And when theyre out of that slump said imp or baby dragon dies tragically.

Combat is always situational. Make their bad rolls have environmental consequences.

From a narrative standpoint, a bad roll doesn't have to be a miss. They can hit a barrel of oil, or fish, and cause it to break open. Now everyone who isn't a fishmonger within the spill area has disadvantage on all attack and save rolls.

Also, as dm, you never have to make your roles public.

Altering the CR is my answer.

Not figuring out CR is why I was not a good DM, among other things. That you mention it at all tells me you probably have some semblance of a handle on it.

dice lack finesse. they are simple and portable and functional. You, as the DM, must provide the missing finesse

You might consider adding a puzzle element to encounters that can lower the effective difficulty with clever maneuvers or strategies.

As an example, fighting in a room with a big chandelier overhead. A player can cut the chandelier at the opportune moment to pin a major adversary, allowing them to coup de grace or simply flaunt their victory to the villain's face.

Or perhaps fighting in a room full of mirrors that allow a clever player to reflect a gaze attack. Or doing Battleship style combat, where you have to pick the square of a hidden enemy, but you guarantee a hit if you guess correctly.

In general, try introducing non-dice resolutions to the scene - guessing a magic word that disables a key piece of enemy tech, baiting enemies into an area or formation before springing a trap,

If all else fails, you can reward them with a wand of fireballs or Staff of the Sun or similar high powered magic item. Doesn't matter how you roll with these, you're going to have some fun.

Another suggestion for an in-universe way to tip the scales in your players' favor would be to invent circumstances where your players' "quick thinking" (read as: heavily signposted narrative elements) could lead to their enemies fighting with some form of disadvantage, without necessarily requiring a good roll.

As an example, say the party have found the bad guys' base in an industrial area of town. They're at the Moston Molasses Market, and it's an unseasonably warm day in the middle of winter (I don't know, let's call it January 15th or equivalent). When the players arrive, they immediately notice that there are these enormous liquid storage silos lining the courtyard, where several mooks are milling. Additionally, without rolling because it's obvious, one tank is literally bursting at the seams, with these long, dark brown streaks oozing out of the rivet joints. Maybe they need to make a skill check to determine this for sure, but it's a reasonable assumption that striking that tank will cause it to burst. Given the size of the object and the foregone conclusion that this thing is gonna burst at some point with or without getting whacked, I would not ask the players for an attack roll if they chose to utilize my signposting. Instead, auto-success, the tank bursts, a wave of molasses escapes, and now the baddies that aren't engulfed in a semi-solid wave of sticky goop at a minimum find themselves fighting in difficult terrain.

Obviously, that's a hyper specific example born out of reading a certain Wikipedia article earlier today, but I hope it illustrates my point. As the architect of the world, the only limit is your creativity when it comes to what challenges your party face. Maybe, before their terrible stealth roll reveals them to the trio of trolls hunting them in the woods, the party overheard two of the trolls discussing how their companion isn't allowed to cook their meals anymore, cause they've both got indigestion. Uh-oh, party gets found, but two of the three enemies have a level of exhaustion (or whatever other nerf you want to slap on that simulates having bubble guts) and their heart isn't really in this fight, so they'll bail at the first sign of resistance. Or, if a player is attentive to your narration, they might describe how their character aims a blow right in the belly of the troll that mentioned their stomach issues. If it hits (and, honestly, if it were me, I'd grant auto-success for the player's listening skills), the troll's eyes go wide, and he flees on his next turn. Depending on the tone of your story, more scatological narration may be included in that action.

In short, if you're concerned the experience of your players prevents you from just tweaking numbers from behind the screen, all you have to do is bend the world to justify your tweaks. Hell, you don't even have to have this ready to go ahead of time. Maybe you planned to have a super easy encounter with a couple of feral wolves on the way to the next village. Nothing challenging, just a reminder that the players are in with wilderness. But, uh-oh, the dice are turning Lassie and friends into Hellhounds with a taste for PC spleen. Rather than letting the campaign end with a whimper, as the heroes of Wherever wind up as puppy chow on a random stretch of dirt track, all of a sudden, the animals cease their attack and perk up their ears. In the distance, between their ragged breaths and the sound of their heartbeat pulsing in their ears, the party hear a howl. The wolves respond in kind and melt into the woods. Maybe with a roll, maybe without, your call, the players realize that the direction of the first howl just so happened to be exactly in the direction of the village they were travelling to. DUN DUN DUNNNNN!

From the your perspective, it was a random encounter gone sideways due to poor luck, and you had to invent a deus ex machina on the fly to prevent an anti-climax. However, from the player's perspective, you have seeded a new narrative hook without relying on dry exposition, and it's one that they might have some personal investment in. You're under no obligation to dissuade them of the error in their assumption. Heck, in spit-balling what could have caused the situation, they may even give you ideas for how you're going to incorporate this new dynamic into whatever you originally had planned for them at the new village.

Idk if any of that is of any use to you, but I hope it at least gives you some ideas for levers you can pull which affect difficulty that are a little more nuanced then, "oh shit, uhhhh I guess this monster's AC is going to be 12 for the rest of this fight".

so a very important question to ask is... do your players want you to thumb the scales, or do they rather want to see where the shitty rolls go? Sometimes, the best solution is to let it play out. Sometimes, the chance of failure makes it more fun, more dramatic. Sometimes, they're emotionally invested in the characters. Maybe instead of goosing the dice rolls or something, give them options for when the dice rolls fail- maybe they become prisoners and can then escape and find some way of poisoning enough people to complete the objective. maybe they can talk their way out of it; or they can fix up some sort of trap or set up some kind of envirmomental thingamdoo.

this is where you need to know what kind of things your players look for, and what you can sneak into the campaign for them to find.

ways to help out a bit might include tossing some healing potions or useful elixirs into the world, either as loot to be found or as drops. that's a bit more subtle. or weapon oils for their weapons. Spell scrolls for the mages, too.

alternatively you could toss them advantage occasionally. They'll know you're doing it, of course, but then, nobody really calls that out. alternatively you can bring in a DMPC that buffs them, and sets them right so they don't have to blow so many spell slots while still letting them guide the action.

as a side note, if you're using a digital dice generator, there may be an issue with it's script. Older rngs or modern ones that focus on speed or 'efficient' coding generally aren't entirely random that sometimes leads to faulty spreads. If you can, have it give you an absurdly large number of rolls and report the counts of each number. GPt-4 gave this result for a 500d20:

As you can see they're all fairly even, but not perfectly so. (it averages out to 10.5, but that's actually somewhat meaningless since true random is going to be... well. random.) in a large pile of rolls, you shouldn't see them be all perfect.