Encounter Design

In [1.25], Dungeon Masters must use art (experience at their craft) and science to design appropriate challenges for player character groups. While rough guidelines can be found in the rules, such as the "level" of the monster and "depth" of the dungeon level, there are few tools to use to "check the math" of the DM's decisions.

Enter Dragon Magazine #39 and #48 and the articles written by Len Lakofka under the heading "Leomund's Tiny Hut". In particular, the essay titled "Mission Control" in Dragon #48 put forward a procedure by which a DM might design a large encounter area (Dungeon, Castle, etc.) centered around a major antagonist and their subordinates. Mr. Lakofka clearly states the procedure still requires an experienced DM to make all final decisions knowing their particular setting and story-based antagonists. However, with a few tweaks, I've found it to be useful to double-check the relative danger of an encounter area before making final stocking decisions. If the danger level is trending too high, modifications can be made or more henchmen/hireling/item help can made available.

What follows is a slightly modified version of Mr. Lakofka's encounter area design procedure. It is still experimental and may not be adhered to for all encounters, especially when the PCs are not necessarily intended use force to overcome the challenge. If an encounter is much higher than the range noted, the DM will take this into account while experience rating is being determined.

Important Note

All "experience points" used to compare PCs to Challenges must be converted to "Class-based Experience Points". For example, a 2nd level single-classed cleric will have 1,501 XP. Whether the cleric is a PC or an opponent, the character needs no conversion. However, "monsters", or creatures without character classes, must be converted to a Class-based Experience Point value. This conversion method is given below.

Step 1. Calculate the Encounter Area Difficulty Range

Begin by calculating the Total Party Experience for all classed PCs and NPCs in the group. 

• This is done by adding together all Class-based Experience Points. For example, a 2nd level cleric PC will have at minimum, 1,501 XP.

  • 1st level characters with classes will add a minimum of 1,000 XP.

  • For non-classed group members use the Monster Experience Points Conversion Method below.

• Add the total Class-based Experience Points together and add 10% (i.e. multiply by 1.10).

This number gives you the Allowable Major Villain Class-based Experience. This is what you will use to determine the strength of the major opponent of the PCs.

This number is also used to determine the Allowable Subordinate Villain Experience used to determine the combined strength of the major villain’s subordinates in the encounter area.

Thus, the total adjusted Class-based Experience Points number which is then doubled will determine the Total Allowable Encounter Area Class-based Experience range. Consider the range of this number to be plus or minus 5%-10% based on environmental or other factors.

Total Allowable Encounter Area Class-based Experience = ((Total Party Experience * 1.10)*2)

Example

The PCs have formed a group that consists of a fighter (3rd), cleric (3rd), ranger (3rd), and magic-user/thief (2nd/3rd). This group is supported by their henchmen: a fighter (1st) and a cleric (1st); Furthermore, they employ three man-at-arms hirelings (soldiers).

• Fighter (3rd)              = 4,001

• Cleric (3rd)               = 3,001

• Ranger (3rd)               = 4,501

• Magic-user/Thief (2nd/3rd) = 5,002

• Fighter (1st)              = 1,000

• Cleric (1st)               = 1,000

• Men-at-arms (x3, 0-level)  = 2,970 ...See the Conversion Method below; using bows; = ((22*45)*3)

Sub-total Class-based Experience Points = 21,475

Total Class-based Experience Points = (21,475 * 1.10) = 23,622.50

Allowable Major Villain Class-based Experience = ~23,622.50 (+/- 5-10%)

Allowable Subordinate Villain Experience = ~23,622.50 (+/- 5-10%)

Total Encounter Area Difficulty Range in Class-based XP = ~47,245 XP (+/- 5-10%)

Thus, using the procedure as a guide, the following examples are valid major villains:

• A evil human thaumaturgist (5th level magic-user) with appropriate magic items (22,501 XP)

• An evil half-orc fighter/assassin 4th/5th level with appropriate magic items (24,001 XP)

• An ousted bugbear chief (4 HD) armed with magic items (24,570 XP; See the Conversion Method below)

• A crazed wereboar warlord (24,680 XP; See the Conversion Method below)

Subordinates might include:

• 10 orcs with battle axes and halberds (3,500 XP)

• 5 orcs with battle axes and crossbows (2,450 XP)

• An orc leader-type (max h.p.) with two-handed sword and crossbow (630 XP)

• An apprentice 2nd level magic-user with appropriate magic items (2,501 XP)

• A group of 10 bandits armed with swords and crossbows (4,000 XP) or one 3rd level fighter with appropriate magic items (4,001 XP)

• A (terrifying) giant weasel companion (8,910 XP)

For a Total Subordinate Villain Experience of 21,991 XP

The Art of Adjustments

Adjustments can be made for the relative physical security of the place, the existence of traps, the alertness of guards, placement (how many are nearby or in the same area), whether the subordinates work together effectively (or not), etc. Also, the more knowledge the PCs have going in, usually better prepares them for the challenge.

The DM will also add local fauna (giant rats, slime, etc.) as well as any additions due to abilities possessed, such as the magic-user's familiar or the result of an animate dead spell—although care must be given to anything on top of the range. The ability to magically summon a creature must be at least considered when determining the difficulty of an encounter—even if this ability if innate and included as a special ability to the base creature.

Possibly the biggest factor to consider is the PCs ability to retreat or recuperate. If the encounter area is set up where the PCs can rest between areas, this alleviates much of the challenge and subordinate XP can be increased. Depending on other factors, 50% or even as high as 100%.

Monster Experience Points Conversion Method

While any NPC villain with class-levels (e.g. fighter, cleric, etc.), major or subordinate, is determined just like a PC, monsters must be converted to Class-based Experience (XP).

To convert a monster to Class-based Experience:

• Find or calculate the monster’s XP Value for being killed/defeated.

• Multiply this number by the Monster Ability Experience Multiplier.

  • The Base Monster Ability Experience Multiplier is 40. The minimum is 30 and the maximum is 150.

  • For monsters with less than 6 hit dice, add 5 to the Base Monster Ability Experience Multiplier for each Special Ability possessed after the first.

  • For monsters with less than 5 hit dice, add 10 to the Base Monster Ability Experience Multiplier for each Exceptional Ability possessed after the first.

  • For monsters with 5 or more hit dice, add 5 to the Base Monster Ability Experience Multiplier for each Exceptional Ability possessed after the first.

  • Major Weaknesses may be assessed as a subtraction of 5 against the Base Monster Ability Experience Multiplier.

Examples

These examples use the table in the section on Dungeonmastering, Experience, Experience Points Value of Monsters. The table uses hit dice as the prime determinant with a Base XP Value (BXPV) added to XP per hit point (XP/HP) then, if a special ability bonus (SAXPB) exists add it, as well as an exceptional ability addition (EAXPA). This campaign also adjusts for major weaknesses (WXPA).

• An orc with 4 hp wielding a battle axe and crossbow = 490 XP = (BXPV 10 + XP/HP (1*4) + SAXPB (4*1) + EAXPA (35*0) + WXPA (-4*1)) * (Base Multiplier 40 + SAXPB ((1-1)*5) + EAXPA ((0)*5) + WXPA ((1)*-5)) = (14) * (35) = 490 XP per orc

• The giant weasel with 22 hp = 8,910 XP = (BXPV 60 + XP/HP (4*22) + SAXPB (25*2) + EAXPA (65*0) + WXPA (-25*0)) * (Base Multiplier 40 + SAXPB ((2-1)*5) + EAXPA ((0)*5) + WXPA ((0)*-5)) = (198) * (45) = 8,910 XP