#### FallenRX

##### Adventurer

Full post here , but this recontextualizes a lot of the debate on the "Encounter day". its not based on Class resources like spell slots, just how much damage they can take in a day, and are expected to take, and heal back with Hit dice. Looking further into his findings on his site here(which show the math proving this), it turns out XP actually is a formula on how much damage/health a monster can do, rounded to certain numbers to suit speed of progression in levels, more on this here.You can calculate XP values for PCs as well. If you do, and average across several encounters, you'll find that the XP thresholds listed in the encounter building rules are just fixed ratios of these values. For Easy encounters this ratio is roughly 15%, for Medium 30%, for Hard 45%, and for Deadly it's roughly 70%. This means, for a Medium difficulty encounter, a typical group of PCs are expected to take around 30% of their maximum hit points in damage, or expend sufficient resources to offset it.

Now, full adventuring days are slightly different than single encounters. For a single encounter, the amount of hit points available to the PCs is their maximum hit points, plus whatever healing they can efficiently do during combat. For a full adventuring day, though, the PCs have all the hit points they can recover outside of combat. The biggest source of these extra hit points is their hit dice. This means for most PCs, their total hit points for a day is roughly twice their maximum hit points.

If you take those ratios I mentioned before, and apply them this new hit point total you neatly get the number of encounters for each encounter difficulty given by the adventuring day calculations.

What all of this means is that the primary resource defining the adventuring day is the PCs hit points, not their other class resources.

Now note, he does say class resources can affect these calculations, but the primary encounter day is designed around mainly HP, and Hit Dice. A Deadly encounter is deadly, because they do enough damage to do about 70% of the players health at that level over a 2-3 round period, and monsters XP values are actually a calcuation of how much damage they can do/take rounded to a number to fit progression speed, Its why XP actually matters in calculating encounter balance, XP is literally a Monsters "Power Level" rounded for rewards to keep progression between level consistent, CR is just a simplification of this to be easier on DM's, so you dont have to do literal algebra to make monsters/calculation monster power.

Now looking into more into his findings at the sites, some interesting confirmations come forward about how classes are balance, since encounters are balanced around HP, Martials surprisingly come out on top, becuase they can always take the most damage, and wizards at the bottom because they can take the least damage, but this changes with class resources, Wizards(and casters) seems to be balanced around the idea that they must spend resources to make up for this using spell slots, but the problem is the same problem as when calculating CR, it doesnt account for non-damaging effects that circumvent whole encounters, i wouldnt be surprised if WOTC simply just calculated the power of them as equal too whatever the average DPR of a damaging spell in the same slot level(Crawford said they do this in a interview about encounter balance a long time about), but definitely leads to a better understanding of the game.

All and all what this means is, if you want to challenge your players more you need to actually damage them equal to the amount the encounter needs, and if you do not damage them, that encounter almost doesnt count toward the "Adventuring Day/XP Budget", and you can basically run more.

Either way this is all fascinating stuff, please correct me if im wrong about anything. If im completely wrong in my understanding of this, ill just delete the post and explain it better.

Tell me your thoughts on this?

TLDR: The games adventuring day and encounter design is primarily done by HP, and Hit Dice, so damage is what matters the most.

Monster XP's are literally their calculated Power Level of how much damage they can take/dish out, just rounded to a number for the sake of progression pacing. Balance your games around the damage done to PC's in a Single Encounter+Resources they can use to recovery.