Challenge Ratings

(Since I almost lost this among the many different older segments, I thought I would rapidly post it to the site, lol.

This is the deep dive into challenge ratings that I did to make them more transparent, more flexible, and enable transposing them from regular 5e to Wyrlde.)

Challenge Ratings

Challenge Ratings are modified for Wyrlde. Overall, Wyrlde’s creatures are tougher, meaner, and more capable of killing a whole party with ease.

There are 42 core Challenge levels, and 10 more that are used for larger creatures, giving a single creature the possibility of being a CR 50. There are no creatures on Wyrlde outside of Powers that have a CR of greater than 50, and no creatures of a greater size on Wyrlde than Titanic.

A typical Wyrlde session will have one or two encounters, and they will be fights that take longer than 3 rounds. The average number of rounds of combat expected is double the party’s average level in a given session, divided between two encounters.

Calculating a Challenge Rating

From time to time you may have a need to calculate the Challenge rating of a creature. For Wyrlde, it is important that you do so when converting a creature not found in the Critteralia. In developing creatures for Wyrlde, the following system is used.

To determine a Creatures challenge Rating you start with the Base Challenge Rating Table. This is the master table for Challenge ratings. It runs from 0 (no challenge) to 50. The Stats given are the baseline for a creature of that CR. Changing the basic scores, increasing or decreasing size, and other factors then modify that base measure and so the CR score.

There are several measures that can modify the Base challenge rating:

Level of Party: The average level of all party members is used to determine the base CR for a given creature. That sets the baseline, which is then modified by all other aspects up or down.
Highest Ability Scores: the highest Ability score of the creature.
Average Ability Sore: the average of all their ability scores.
Armor Class: Is the armor class greater or lesser than the base for that creature This impacts CR.
Proficiency Bonus: The highest proficiency bonus of the creature.
Size: How big is it? Wyrlde has many more sizes of creatures and size determines the kind of hit die they use, and some critters have either bigger or smaller hit dice, which impacts the CR. The size of a creature also determines the size of the damage die it uses.
Hit Dice: The number of and type of hit dice the creature has.
Attack Bonus: the highest attack bonus of the creature.
Save DC: The highest Save DC of the creature.
XP Value: The anticipated XP Value of the Creature.
Attacks: How many attacks per round does the creature have? Some creatures have no attacks, others have many more than 1.
Magic: What Degrees of complexity does the critter have the ability to use based on spells or powers? Note that special abilities and the like do count for this feature, even if they don’t normally use magic spells. So Psionics, Runes, Words of Power, and similar elements apply as well.
Lairs: A creature fought in a lair is more difficult to deal with than one outside of it. Simple Lairs are easier, more well defend and difficult to deal with lairs are harder.
Swarms have a special category. A Swarm may increase the CR of a given creature based on the number of creatures each party member is dealing with. Note that swarms are applied only for for Bitty and Micro size creatures; larger ones will use the normal number of creatures factor.

Number of Creatures

The number of creatures that a PC can face is determined by their level against the final CR for the creature they are facing. This one is expressed as a multiplier in the table below. Multiply the size of the party by the number shown and round down. That is how many creatures of that level the party should face. You can flip this as well: 100 Apprentices might be able to handle a CR 33 critter, 20 might be able to handle a CR 8. This is how one balances or determines the number of creatures to push against a party in an encounter.

Ratio of Monsters to Party

Degree of Mastery	Monster Challenge Rating
Degree of Mastery	0 to 1/2	1 to 8	9 to 16	17 to 24	25 to 32	33 to 40	41 to 50
Apprentice	1	0.05	0.04	0.03	0.02	0.01	0.001
Novice	1.1	1	0.33	0.22	0.10	0.05	0.01
Professional	1.3	1.1	1	0.33	0.22	0.10	0.03
Adept	1.5	1.3	1.1	1	0.33	0.22	0.05
Master	1.7	1.5	1.3	1.1	1	0.33	0.10
Grandmaster	2	1.7	1.5	1.3	1.1	1	0.25

Balancing

Balancing CR is based on the combined hit points of the party and the foes, followed by the combined average damage of each side. To determine average damage, multiply one half the damage die by the number of attacks of the creature. A balanced encounter on Wyrlde is considered to have a Ration of Foes to Party of 1.5:1. The creatures should have a ratio of 1.5 on HP and Damage over the party.

Die Chain

The Die Chain for Monsters is d4, d6, d8, d10, d12, d14, d16, d18, d20, d24, d30. Moving up or down that changes the CR as well, with the lowest a d4, the highest a d30.

Customizing a Creature

The Average Level of the Party determines the starting CR for a given encounter. Using the Ratio, you can get an idea of how many creatures at base the party should encounter of that general CR.

There are two CR ranks for each level of the party, giving some flexibility. Once you have that, you can look to any creature with a CR provided in either 5e or Wyrlde and begin to alter the creature’s basic stats and abilities, changing the creature.

The absolute highest CR a creature can have is 50, the lowest is 0. The Maximum number of shifts you can make with a given creature is 12 in either direction, and such a shift cannot take a creature below 0 or above 50. Thus, a CR 0 creature cannot be raised above a CR 11 by tweaking its features. This is due in large part to the Die Scale and its operation, which the CR system relies on.

The vast majority of creatures will be between 0 and 40, overall. CRs which run from 41 to 50 are exceptional end cases and note that the minimum size of a Level 20 party facing a CR41 creature is 4 – that also presumes that said creature is the only one they fight. A party of 5^th level characters would need to be 33 people in size at minimum to tackle them.