Thursday, August 17, 2023

Comparing Encounter Building in Xanathar's and Flee, Mortals!

 So, the encounter building rules in Xanathar's Guide to Everything were a welcome and far easier-to-use system for balancing encounters than the ones found in the 2014 DMG. The DMG version, I always felt, really emphasized fights against single monsters, which tended to mean that if the party rolled well on initiative, they would kill their foe before it could do much to them. Xanathar's created a kind of "equivalent monsters per player of a certain level" system, with charts showing how many CR 1 creatures you could add to an encounter for each, say, 6th level player.

Flee, Mortals! further simplifies things, giving you a total CR budget for each player in the party. In fact, this winds up being similar to the original system, but without the big penalties for having multiple monsters. In my early days of encounter design, I'd eagerly bring in some, say, Orc Eye of Gruumsh (or Rokotek, in my setting, where the dominant orcish culture began worshipping a Great Old One) which was all I could afford to have my three-person level 2 party fight.

These days, rather than having a single such orc, I'd probably have a group like that (admittedly small and low-level) face off against a handful of standard Orc creatures, with maybe some wolves mixed in to vary things up.

So, given that I haven't used the DMG encounter-building math since Xanathar's came out, I figured I'd compare the latter with FM's system. We'll do this at a couple different breakpoints - somewhere in the middle of each tier of play.

Each system also has a special set of rules for solo monsters, which we might look at after we do the group-fight ones.

Notably, though, Xanathar's system does not have variations for difficulty - you kind of have to play it by ear if you want to tune the difficulty up or down. FM's system explicitly warns that it creates harder fights - a Standard encounter should be a significant drain on a party's resources, and a Hard one should carry a real risk of character death in it. We can look at Easy and Standard encounters from FM to see where the Xanathar ones land.

We're going to assume here we've got a party of four players, and that the party is fairly balanced and normally equipped for their level.

Level 2:

I wrote a post yesterday about building a full day of adventure for a level 2 party. But let's look specifically at the CR budget for standard encounters.

In FM, a level 2 character is worth 1/8 CR in an easy encounter or 1/4 in a standard one. Thus, our total CR for an easy encounter would be 1/2, or 1 in a standard encounter.

In Xanathar's, the ratio for 2nd level characters and 1/8 monsters is 1:3, meaning we could have three 1/8 monsters for each player character. For 1/4 monsters, the ratio is 1:2. In other words, with those totaled, if we use a lot of 1/8 monsters, we could have twelve of them, or a total CR of 1.5. If we use 1/4 monsters, we can have two of them per player, making for a total CR of 2.

    So, I'll actually confess I'm surprised here that the Xanathar's rule is less forgiving. Granted, tier 1 is a very unforgiving tier of play. I usually don't have players go through more than two fights in a day at tier 1, unless some of the fights are truly trivial.

Level 8:

Just on the higher end of tier 2, level 8 is when you typically can have your main ability score maxed out (unless you decide to go for a feat or something - or if you rolled really good stats early on).

In FM, a level 8 character is worth 2.5 CR in an easy encounter, or 3 in a standard encounter. So, with four players, we're looking at 10 or 12 total CR.

Xanathar's gives us a ratio of 1:2 for CR 2 creatures, 1:1 for CR 3 creatures, and 2:1 for CR 4 creatures. In other words, if we're using CR 2 creatures, we can afford 8 of them, bringing our total CR to 16. If our creatures are CR 3, we would get a total of 12. And if we're using CR 4 creatures, we need two players for each of them, giving us a total CR of 8.

    So, here's the interesting thing: if the DMG system really pushed us to having fewer, higher CR creatures, the Xanathar's system is pushing us in the opposite direction. This system seems to build for lots of less powerful creatures.

Level 13:

Now, up into the higher levels, we're looking at some significantly powerful player characters, and the CR budget is getting a lot higher.

FM's system gives us 5 CR per player in easy encounters and 5.5 in standard encounters. So we're looking at 20 total CR or 22.

Xanathar's puts CR 5 or 6 as equivalent to a single level 13 player - which would give us a 20-24 total CR range. If we wanted higher-CR creatures, CR 7 gives us a ratio of 2:1, so we could have two CR 7 creatures, for a total budget of 14. If we went with lower CR, we could have two CR 4 creatures for each player, giving us 8 creatures and a total CR of 32.

Level 19:

All right, I think I've figured out the difference between these systems by now, but just for the sake of completion, let's finish the job.

FM gives us 8 CR per character in easy encounters and 8.5 for standard, for a total budget of 32 or 34.

Xanathar's gives us 2 CR 6 creatures per character, one CR 7-9 creature per character, or 2 characters per CR 10 creature. So, that could give us anywhere from a total CR of 48 if it's all CR 6 creatures or just 20 if it's two CR 10 creatures.

    Now, I realize that the way I've framed this betrays a bias toward the FM system. I think the issue I've identified with the Xanthar's system is that the swing in ratio between CRs can get pretty huge. While the difference between a CR 1 and a CR 2 creature is pretty big, the difference between a CR 6 and a CR 7 one is not, but at certain breakpoints, the Xanathar system considers the latter two be twice as much of a challenge as the former.

What the FM system does is smooth out those issues - when you're just totaling CR, 6 and 7 are rightfully near one another - let's say you are looking for a total CR of 20. You could use three CR 6 monsters and then enough to fill in that last two, or you could use two CR 7 monsters and then maybe even use one of those CR 6 creatures to fill it in.

What's funny is that I think the DMG rules, which were based on adding up XP (XP being linked to CR) was meant to accomplish this same basic idea, but somehow, the FM system feels the most elegant and also flexible.

Again, this is largely theoretical. FM will be more forgiving of throwing very tough monsters at your party, and less forgiving on using lots of lower-CR monsters. That said, in my experience mostly using the Xanathar's system, I have found that it often tempts me to make enormous fights (especially when I have a party that usually has six players and can roll as deep as eight) with tons of weaker enemies that make the fights go very long. I suspect FM's system will make me feel more confident in having big beefy monsters.

That said, there are some high-CR monsters who can be shut down pretty easily. A non-legendary creature without high wisdom saves can be taken out of a fight with something like Hypnotic Pattern.

It all remains to be seen. I have a major boss fight I'm planning that will involve a total of four monsters, but I still suspect it will be a very difficult one - though I'm taking a risk and using a stat block that does not have any legendary resistance or villain actions as the main "boss," and hoping that the minions will truly be enough to make him memorably difficult. (Spoiler alert - it's going to be the FM Lich with a pair of homebrewed stat blocks for a Phyrexian Obliterator and a pair of Phyrexian Negators - the former being a Brute, or possibly Soldier, while the latter are skirmishers).

Especially looking at all the high-CR monsters from Bigby's, having a system that makes using such creatures easier is appealing. The key, though, is also having confidence that your players will be able to handle it when, say, the sorcerer takes an absolute barrage of spell attacks (like what happened on Monday when one of the two storm sorcerers tried to get the drop on a group of Lacunae that weren't initially actually hostile, but trying to hide as inert statues, and he got hit with I think four of their Grief-Eater attacks, one of which was a crit, and each of which deal an average of 29 damage. Miraculously, he didn't go down, and soon the fight was resolved with Persuasion checks, other than the Flintmoth Swarm that the fighting had aroused, which had to be killed conventionally.)

Of course, this is all more of an art than a science. But I do think it's better to use a system where you can't double your monsters simply from dropping from CR 7 to CR 6. Xanathar's was a huge step up in ease of use, but I think FM's system is likely what I'll be using moving forward, pending more familiarity with it.

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