Say your player’s characters keep dying? Do you make the encounters easier? Do you relocate the PC’s? Do you keep running them through the gauntlet until a set of characters rises to the top?
In the most recent (at the time of writing) episode of Nevre: Yeodiax (which is set in a future of the setting for Fractured Mountains) I had to decide whether to send the group back to the wilderness, where they keep dying, or keep them in the city, where they have a chance to level up some before heading back out?
My solution was to keep them in the city and send them on a short filler quest to deliver a chest that turned out to be [spoilers]. (If you wish to watch the episode it’s on my YouTube channel linked at the end of this post.)
My solution was to send them somewhere I knew they were more likely to survive. I also toned down the encounters a little, but forgot to take into account that we had an extra player for the session. Survival rates increase greatly with just one more character.
There are many places and times that just pulling the characters out of the fire isn’t an option that allows the players to keep their buy-in. I had the only survivor captured and dragged to the goblin caves near the city, but that’s not always an option.
If I didn’t have somewhere close by to send the characters I probably would have started to tone down the encounters a little. I had already started doing this at the beginning of the campaign. I removed the ability for kobolds to use pack tactics because I had instituted flanking. Getting the characters thinking about optimal placement to both activate flanking and avoid being flanked goes out the window when enemies don’t have to position for advantage.
An easy way to tone down encounters is to have the enemies use bad tactics. Instead of flanking at the start of the battle they just spread out and try to take on characters one to one. The players are then free to disengage and position for advantage if they wish. The only exception to this is that the caster should not be targeted and the monsters that would target them should go after the fighter/barbarian/monk/etc.
So, when it comes to combat, to make it easier for your players either get them to move somewhere that has less difficult encounters or use less optimal tactics against them. There’s also the chance that your players aren’t tactically minded and using less optimal tactics doesn’t change anything. In that case I recommend lowering the CR of future encounters, little by little until you reach a sweet spot. Finding the CR sweet spot is difficult and CR is more of a guideline than a ruler.
Likewise, you can increase the combat difficulty, if the characters are breezing through things that you want to slow them down, by doing the opposite. Start using better tactics. If that doesn’t work then slightly increase the CR.
But what about if they keep failing your skill-based challenges? This is maybe an easier question. There are recommended difficulties for skills in the 5e DMG. Do not scale these up based on level unless someone is proficient in that skill, and then only by one or two. It may seem like the characters are failing a lot, but remember that their ideas on how to handle the situation should give modifiers to the roll.
For example, there’s three doors in front of the characters. Two lead to traps and one leads forward. There is a riddle in front of them which, when solved, tells them which door is the correct one. If the group’s survivalist wants to make the check easier by finding which door has the most air flow coming from beneath it, let him roll and if he succeeds give them a +2 modifier for solving the riddle (or a hint if you don’t want them to roll to solve the riddle).