Encounter Level / Challenge Rating / Party Strength
Encounter Level / Challenge Rating / Party Strength
Here’s an approach to encounter levels that Justin would love. (Number crunching makes him happy.)
p = CR {if CR < =2} or 2^(CR/2) {if CR > 2}
EL = SIGMA(p) {if SIGMA(p) < =2} or 2 * ln (SIGMA(p))/ln(2) {if SIGMA(p) > 2}
If the group consists of PC’s instead of monsters, substitute their adjusted levels for CR.
For example, if your party consists of 5 members, level 4, 4, 5, 7, 10, then the total party is equivalent to EL 11.66. An appropriate challenge would be EL 7.66.
To get a fairly precise answer, you need a calculator that can raise a number to an arbitrary power (X ^ Y) and can take natural logs (ln). Windows contains such a calculator under Programs, Accessories (but you need to switch it from a “Standard” calculator to a “Scientific” one). If you’d rather not wrestle with advanced functions like this, you can get an approximate answer by using basic arithmetic as described below.
Here is a step by step procedure:
1. For each member of the group, compute how many power points it is worth. If the CR or ECL is <= 2, then the points equal the CR or ECL. If the CR or ECL is greater, then the points equal 2 ^ (CR/2), or 2 ^ (ECL/2). Or you can use this chart:
CR or ECL 2 or less = CR or ECL
CR or ECL 3 = 2.8
CR or ECL 4 = 4
CR or ECL 5 = 5.7
CR or ECL 6 = 8
CR or ECL 7 = 11.3
CR or ECL 8 = 16
CR or ECL 9 = 22.6
CR or ECL 10 = 32
CR or ECL 11 = 45.3
CR or ECL 12 = 64
CR or ECL 13 = 90.6
CR or ECL 14 = 128
CR or ECL 15 = 181
CR or ECL 16 = 256
CR or ECL 17 = 362
CR or ECL 18 = 512
CR or ECL 19 = 724
CR or ECL 20 = 1024
(If the group consists of monsters, use CR; if it consists of PC’s, use ECL).
2. Add up all of the points for the group. Call this P.
3. The EL of the entire group (if encountered as monsters) is equal to 2 * ln(P)/ln(2) {Exception: if P is 2 or less, then the EL equals P}. Or, use the chart in reverse. For instance, a group with 600 pts would be somewhere between EL 18 and EL 19.
4. To find the EL of an “appropriate encounter” for a group of PC’s, divide P by four before plugging it into the formula described in (3). Or, divide P by four before consulting the
chart. For instance, 600/4 = 150 pts, which is somewhere between EL 14 and EL 15.
Example:
The party consists of a Clr 5, Rog 6, Sor 6. The points are 5.7, 8, and 8. The total points are 21.7. According to the chart, this is very close to EL 9; using the formula results in EL 8.88.
One quarter of 21.7 is 5.425, which is nearly EL 5 (or 4.88, using the formula). This means that the party has roughly the same power as a party of four 4.88-th level characters. An appropriate encounter will be EL 4.88; a difficult encounter will be EL 6.88; and a deadly encounter will be EL
8.88.
{Joel Note:
Appropriate (Party EL - 4) approximately 15 of these = 1 level
Difficult (Party EL - 2) approximately 8 of these = 1 level
Deadly (Party EL) approximately 4 of these = 1 level
}
Suppose you want a normal encounter that includes two ogres, both CR 2. Since two ogres are EL 4 (4 pts), you’ll want to add 0.88 more points. This can be achieved by adding an orc (CR 1/2 = 0.5 pts) and two kobolds (CR 1/6 = 0.17 pts each).