D&D 5E Encounter Budgets

[andreww]

I am trying to work out how the encounter budgets work, specifically with reference for the multiplication for additional monsters.

As written the rules suggest that the budget is multiplied based on the total number of monsters in the encounter. I wondered if this was right or whether the multiplication should be by group. Lets take a quick example to help illustrate.

Lets say you want an encounter with an Archmage (Challenge 12, 8400xp), backed up by a pair of Chain Devils (Challenge 8, 3900xp) and a dozen Orogs (Challenge 2, 450xp).

15 creatures makes for a horde and multiplies the xp value by 4 for deciding the challenge of the encounter. That makes:

8400
7800
5400
------
21600

Multiplied by four that comes out at 86400xp which is a deadly encounter for about 7 level 20 PC's. Surely that cannot be intended? Even if we limit it to the Archmage and a single Chain Devil we are multiplying by 1.5 for a final xp rating of 18450 which is a deadly encounter for 4 level 12 PC's.

If we assume that we only apply the multiplier for the group of monsters then our initial encounter ends up as:

8400
11700 (7800 x 1.5)
21600 (5400 x 4)
-------------------
41700

That is still a crazily high xp value as it represents a deadly encounter for a group of level 19 characters.

Am I missing something here or does the horde 4x calculation rather distort things?

The single archmage and devil encounter would come out at 12300xp if neither is multiplied which represents a hard encounter for a group of level 12 PC's.

 

[Theovis]

Mixing challenge scores is problematic, it doesn't really work when you have a bunch of jerks that are way below the other monsters.

The guidelines in the latest Basic specifically mention this:

When making this calculation, don’t count any
monsters whose challenge rating is significantly below
the average challenge rating of the other monsters in the
group unless you think the weak monsters significantly
contribute to the difficulty of the encounter.

They aren't really neglible, so I wouldn't ignore them, but maybe count the orogs at about half each for your multiplier, making the encounter the equivalent of 8 monsters, so a 2.5 multiplier.

 

[Elric]

The encounter design guidelines are very flawed and overstate encounter difficulty when you have monsters at very different CRs. I haven't looked at the update a week ago to the DM Basic Guide in detail, but it looks much the same.

I recommend Gobelure's thread on how to modify the encounter design guidelines to fix this problem, so that you don't need an "encounter XP multiplier." http://www.enworld.org/forum/showthread.php?367697-Encounter-difficulty-how-to-fix-it The key is that in Gobelure's new tables PC and monster power scales more slowly with CR/levels, so that you don't need the "fudge factor" of a multiplier.

Here's how I described the issue in that thread:

It seems to me that PC and monster power doesn't scale as fast in general as the XP numbers alone would imply (e.g., a CR 5 Hill Giant worth 1,800 XP is not as deadly as 4 CR 2 Ogres worth 450 XP each). So large numbers of lower CR monsters would be too strong relative to what the XP total suggests.

The encounter XP multiplier (basic DM guide, p. 57) helps to address that design flaw. However, the XP multiplier is itself flawed (as an encounter with an Adult Red Dragon and 3 Kobolds demonstrates).

My take is that some monsters are particularly dangerous in groups (e.g., with their own kind, like Intellect Devourers, or with any melee combatant, like Hobgoblins). Those should have been handled with special guidelines in their stat blocks (CR varies based on group composition), and XP should have simply scaled more slowly as CR increased (with the corresponding decrease in the XP budget encounter guidelines), thus obviating the need for a multiplier.