Besides the ongoing 4th edition D&D campaign I run at my house, I play some 5th edition Dungeons & Dragons at a roleplaying club in the city. And now I decided to run a 5E adventure there as well. While I do like the tactical combat, good balance, and many options that 4th edition D&D has, 5E is definitively more popular, faster, and easier to prepare as a DM.

However one thing I'm still struggling with is building balanced encounters, which might be a problem for the adventure I'm planning. Between the DMG, the encounter building rules in Unearthed Arcana, and the advice you get on the internet there are big differences. The fundamental problem here is that 5th edition re-introduced a strong imbalance between casters and non-casters that 4th edition had removed. A wizard or similar magic-using class casting actual spells (not cantrips) every round has a far higher damage output than the weapon-using classes, but then eventually runs out of spell slots and is reduced to relatively harmless cantrips.

As a result, if you use the official rules the encounters tend to be somewhat too easy, unless you prevent the characters from resting and do the suggested 5 encounters between long rests. That works reasonably well in some settings, like dungeons, but a lot less well in other settings. If you want a mix of combat encounters and role-playing encounters, preventing players from resting becomes a somewhat artificial and strained exercise. You need to invent time constraints or interruptions, just so that the encounters don't become too easy for an alpha-striking wizard. And then you need to invent situations that enable the group to rest after 5 encounters or so despite the constraints you put up earlier.

So no wonder that if you look elsewhere on the internet, people consider the balanced encounters of the official rules as too easy, and prefer higher challenge ratings. However at higher challenge ratings another fundamental property of 5th edition is aggravated: 5E is the most unpredictable version of Dungeons & Dragons due to combat mathematics. Many monsters as well as many spells of players deal a lot of dice of damage, and critical hits double the number of dice. Friday my level 3 paladin was fighting a monster that only had a 20% chance to hit him in his plate armor and shield, but dealt on average 20 points of damage compared to the 28 maximum hitpoints of my character, and had multiple attacks. Even with using all my healing power on myself on my turn, the monster knocked me unconscious by hitting me 3 times in 3 rounds with some lucky rolls.

For the adventure I'm designing, I really don't want to use monsters that can take more than half of somebody's hit points with a single hit, and one-shot a full health character on a critical hit. But if you compare the monsters in the Monster Manual with the "Monster Statistics by Challenge Rating" table on page 274 of the Dungeon Masters Guide, it is clear that most monsters are built around a low defensive challenge rating and a high offensive challenge rating. That results in the typical 5E "fast combat" experience, but is somewhat of a gamble for encounter balance. If every fight lasts only a few rounds with few attacks, the same monster can end up being a complete pushover with unlucky rolls or cause a total party kill on high rolls. A lot of DMs get around that problem by fudging dice. I don't like that method, because it is very hard not to overdo it and basically take the game out of D&D. It also is an admission of defeat, you fudge dice because the mathematics of the system with rolling dice just don't work.

For my adventure I am using a mix of official and self-created monsters. And the monsters I made will be a little less 5E and a little more 4E, lasting a bit longer in combat but also draining the life of the players a bit more slowly. I hope that will solve several of the problems of 5E, on the one side teaching the casters not to use spell slots every turn, while on the other side being a bit more predictable and letting me roll dice in the open. The adventure is designed to have 50:50 combat encounters and role-playing encounters, and if every combat was finished after 2 turns that would be not enough time spent in combat. It isn't so much the number of encounters between rests that is needed by the 5th edition rules, but rather the number of combat turns between rests.