The heart of any adventure is its encounters. An encounter is any event that puts a specific problem before the PCs that they must solve. Most encounters present combat with monsters or hostile NPCs, but there are many other types—a trapped corridor, a political interaction with a suspicious king, a dangerous passage over a rickety rope bridge, an awkward argument with a friendly NPC who suspects a PC has betrayed him, or anything that adds drama to the game. Brain-teasing puzzles, roleplaying challenges, and skill checks are all classic methods for resolving encounters, but the most complex encounters to build are the most common ones—combat encounters.
When designing a combat encounter, you first decide what level of challenge you want your PCs to face, then follow the steps outlined below.
Determine the average level of your player characters—this is their Average Party Level (APL for short). You should round this value to the nearest whole number (this is one of the few exceptions to the round down rule). Note that these encounter creation guidelines assume a group of four or five PCs. If your group contains six or more players, add one to their average level. If your group contains three or fewer players, subtract one from their average level. For example, if your group consists of six players, two of which are 4th level and four of which are 5th level, their APL is 6th (28 total levels, divided by six players, rounding up, and adding one to the final result).
Challenge Rating (or CR) is a convenient number used to indicate the relative danger presented by a monster, trap, hazard, or other encounter—the higher the CR, the more dangerous the encounter. Refer to Table: Encounter Design to determine the Challenge Rating your group should face, depending on the difficulty of the challenge you want and the group's APL.
Determine the total XP award for the encounter by looking it up by its CR on Table: Experience Point Awards. This gives you an “XP budget” for the encounter. Every creature, trap, and hazard is worth an amount of XP determined by its CR, as noted on Table: Experience Point Awards. To build your encounter, simply add creatures, traps, and hazards whose combined XP does not exceed the total XP budget for your encounter. It's easiest to add the highest CR challenges to the encounter first, filling out the remaining total with lesser challenges.
For example, let's say you want your group of six 8th-level PCs to face a challenging encounter against a group of gargoyles (each CR 4) and their stone giant boss (CR 8). The PCs have an APL of 9, and Table: Encounter Design tells you that a challenging encounter for your APL 9 group is a CR 10 encounter—worth 9,600 XP according to Table: Experience Point Awards. At CR 8, the stone giant is worth 4,800 XP, leaving you with another 4,800 points in your XP budget for the gargoyles. Gargoyles are CR 4 each, and thus worth 1,200 XP apiece, meaning that the encounter can support four gargoyles in its XP budget. You could further refine the encounter by including only three gargoyles, leaving you with 1,200 XP to spend on a trio of Small earth elemental servants (at CR 1, each is worth 400 XP) to further aid the stone giant.
Adding NPCs: Creatures whose Hit Dice are solely a factor of their class levels and not a feature of their race, such as all of the PC races detailed in Races, are factored into combats a little differently than normal monsters or monsters with class levels. A creature that possesses class levels, but does not have any racial Hit Dice, is factored in as a creature with a CR equal to its class levels –1. A creature that only possesses non-player class levels (such as a warrior or adept) is factored in as a creature with a CR equal to its class levels –2. If this reduction would reduce a creature's CR to below 1, its CR drops one step on the following progression for each step below 1 this reduction would make: 1/2, 1/3, 1/4, 1/6, 1/8.
High CR Encounters: The XP values for high-CR encounters can seem quite daunting. Table: CR Equivalencies provides some simple formulas to help you manage these large numbers. When using a large number of identical creatures, this chart can help simplify the math by combining them into one CR, making it easier to find their total XP value. For example, using this chart, four CR 8 creatures (worth 4,800 XP each) are equivalent to a CR 12 creature (worth 19,200 XP).
Ad Hoc CR Adjustments: While you can adjust a specific monster's CR by advancing it, applying templates, or giving it class levels, you can also adjust an encounter's difficulty by applying ad hoc adjustments to the encounter or creature itself. Listed here are three additional ways you can alter an encounter's difficulty.
Characters advance in level by defeating monsters, overcoming challenges, and completing adventures—in so doing, they earn experience points (XP for short). Although you can award experience points as soon as a challenge is overcome, this can quickly disrupt the flow of game play. It's easier to simply award experience points at the end of a game session—that way, if a character earns enough XP to gain a level, he won't disrupt the game while he levels up his character. He can instead take the time between game sessions to do that.
Keep a list of the CRs of all the monsters, traps, obstacles, and roleplaying encounters the PCs overcome. At the end of each session, award XP to each PC that participated. Each monster, trap, and obstacle awards a set amount of XP, as determined by its CR, regardless of the level of the party in relation to the challenge, although you should never bother awarding XP for challenges that have a CR of 10 or more lower than the APL. Pure roleplaying encounters generally have a CR equal to the average level of the party (although particularly easy or difficult roleplaying encounters might be one higher or lower). There are two methods for awarding XP. While one is more exact, it requires a calculator for ease of use. The other is slightly more abstract.
Exact XP: Once the game session is over, take your list of defeated CR numbers and look up the value of each CR on Table: Experience Point Awards under the “Total XP” column. Add up the XP values for each CR and then divide this total by the number of characters—each character earns an amount of XP equal to this number.
Abstract XP: Simply add up the individual XP awards listed for a group of the appropriate size. In this case, the division is done for you—you need only total up all the awards to determine how many XP to award to each PC.
Story Awards: Feel free to award Story Awards when players conclude a major storyline or make an important accomplishment. These awards should be worth double the amount of experience points for a CR equal to the APL. Particularly long or difficult story arcs might award even more, at your discretion as GM.
As PCs gain levels, the amount of treasure they carry and use increases as well. The game assumes that all PCs of equivalent level have roughly equal amounts of treasure and magic items. Since the primary income for a PC derives from treasure and loot gained from adventuring, it's important to moderate the wealth and hoards you place in your adventures. To aid in placing treasure, the amount of treasure and magic items the PCs receive for their adventures is tied to the Challenge Rating of the encounters they face—the higher an encounter's CR, the more treasure it can award.
Table: Character Wealth by Level lists the amount of treasure each PC is expected to have at a specific level. Note that this table assumes a standard fantasy game. Low-fantasy games might award only half this value, while high-fantasy games might double the value. It is assumed that some of this treasure is consumed in the course of an adventure (such as potions and scrolls), and that some of the less useful items are sold for half value so more useful gear can be purchased.
Table: Character Wealth by Level can also be used to budget gear for characters starting above 1st level, such as a new character created to replace a dead one. Characters should spend no more than half their total wealth on any single item. For a balanced approach, PCs that are built after 1st level should spend no more than 25% of their wealth on weapons, 25% on armor and protective devices, 25% on other magic items, 15% on disposable items like potions, scrolls, and wands, and 10% on ordinary gear and coins. Different character types might spend their wealth differently than these percentages suggest; for example, arcane casters might spend very little on weapons but a great deal more on other magic items and disposable items.
Table: Treasure Values per Encounter lists the amount of treasure each encounter should award based on the average level of the PCs and the speed of the campaign's XP progression (slow, medium, or fast). Easy encounters should award treasure one level lower than the PCs' average level. Challenging, hard, and epic encounters should award treasure one, two, or three levels higher than the PCs' average level, respectively. If you are running a low-fantasy game, cut these values in half. If you are running a high-fantasy game, double these values.
Encounters against NPCs typically award three times the treasure a monster-based encounter awards, due to NPC gear. To compensate, make sure the PCs face off against a pair of additional encounters that award little in the way of treasure. Animals, plants, constructs, mindless undead, oozes, and traps are great “low treasure” encounters. Alternatively, if the PCs face a number of creatures with little or no treasure, they should have the opportunity to acquire a number of significantly more valuable objects sometime in the near future to make up for the imbalance. As a general rule, PCs should not own any magic item worth more than half their total character wealth, so make sure to check before awarding expensive magic items.
While it's often enough to simply tell your players they've found 5,000 gp in gems and 10,000 gp in jewelry, it's generally more interesting to give details. Giving treasure a personality can not only help the verisimilitude of your game, but can sometimes trigger new adventures. The information on the below can help you randomly determine types of additional treasure—suggested values are given for many of the objects, but feel free to assign values to the objects as you see fit. It's easiest to place the expensive items first—if you wish, you can even randomly roll magic items, using the tables in Magic Items, to determine what sort of items are present in the hoard. Once you've consumed a sizable portion of the hoard's value, the remainder can simply be loose coins or non-magical treasure with values arbitrarily assigned as you see fit.
Coins: Coins in a treasure hoard can consist of copper, silver, gold, and platinum pieces—silver and gold are the most common, but you can divide the coinage as you wish. Coins and their value relative to each other are described at the start of Equipment.
Gems: Although you can assign any value to a gemstone, some are inherently more valuable than others. Use the value categories below (and their associated gemstones) as guidelines when assigning values to gemstones.
Low-Quality Gems (10 gp): agates; azurite; blue quartz; hematite; lapis lazuli; malachite; obsidian; rhodochrosite; tigereye; turquoise; freshwater (irregular) pearl
Semi-Precious Gems (50 gp): bloodstone; carnelian; chalcedony; chrysoprase; citrine; jasper; moonstone; onyx; peridot; rock crystal (clear quartz); sard; sardonyx; rose, smoky, or star rose quartz; zircon
Medium Quality Gemstones (100 gp): amber; amethyst; chrysoberyl; coral; red or brown-green garnet; jade; jet; white, golden, pink, or silver pearl; red, red-brown, or deep green spinel; tourmaline
High Quality Gemstones (500 gp): alexandrite; aquamarine; violet garnet; black pearl; deep blue spinel; golden yellow topaz
Jewels (1,000 gp): emerald; white, black, or fire opal; blue sapphire; fiery yellow or rich purple corundum; blue or black star sapphire
Grand Jewels (5,000 gp or more): clearest bright green emerald; diamond; jacinth; ruby
Non-magical Treasures: This expansive category includes jewelry, fine clothing, trade goods, alchemical items, masterwork objects, and more. Unlike gemstones, many of these objects have set values, but you can always increase an object's value by having it be bejeweled or of particularly fine craftsmanship. This increase in cost doesn't grant additional abilities—a gem-encrusted masterwork cold iron scimitar worth 40,000 gp functions the same as a typical masterwork cold iron scimitar worth the base price of 330 gp. Listed below are numerous examples of several types of nonmagical treasures, along with typical values.
Fine Artwork (100 gp or more): Although some artwork is composed of precious materials, the value of most paintings, sculptures, works of literature, fine clothing, and the like come from their skill and craftsmanship. Artwork is often bulky or cumbersome to move and fragile to boot, making salvage an adventure in and of itself.
Jewelry, Minor (50 gp): This category includes relatively small pieces of jewelry crafted from materials like brass, bronze, copper, ivory, or even exotic woods, sometimes set with tiny or flawed low-quality gems. Minor jewelry includes rings, bracelets, and earrings.
Jewelry, Normal (100–500 gp): Most jewelry is made of silver, gold, jade, or coral, often ornamented with semi-precious or even medium-quality gemstones. Normal jewelry includes all types of minor jewelry plus armbands, necklaces, and brooches.
Jewelry, Precious (500 gp or more): Truly precious jewelry is crafted from gold, mithral, platinum, or similar rare metals. Such objects include normal jewelry types plus crowns, scepters, pendants, and other large items.
Masterwork Tools (100–300 gp): This category includes masterwork weapons, armor, and skill kits—see Equipment for more details and costs for these items.
Mundane Gear (up to 1,000 gp): There are many valuable items of mundane or alchemical nature detailed in Equipment that can be utilized as treasure. Most of the alchemical items are portable and valuable, but other objects like locks, holy symbols, spyglasses, fine wine, or fine clothing work well as interesting bits of treasure. Trade goods can even serve as treasure—10 pounds of saffron, for example, is worth 150 gp.
Treasure Maps and Other Intelligence (variable): Items like treasure maps, deeds to ships and homes, lists of informants or guard rosters, passwords, and the like can also make fun items of treasure—you can set the value of such items at any amount you wish, and often they can serve double-duty as adventure seeds.
Magic Items: Of course, the discovery of a magic item is the true prize for any adventurer. You should take care with the placement of magic items in a hoard—it's generally more satisfying for many players to find a magic item rather than purchase it, so there's no crime in placing items that happen to be those your players can use! An extensive list of magic items (and their costs) is given in Magic Items.
Although you should generally place items with careful consideration of their likely effects on your campaign, it can be fun and save time to generate magic items in a treasure hoard randomly. You can “purchase” random die rolls of magic items for a treasure hoard at the following prices, subtracting the indicated amount from your treasure budget and then rolling on the appropriate column on Table: Random Magic Item Generation in Magic Items to determine what item is in the treasure hoard. Take care with this approach, though! It's easy, through the luck (or unluck) of the dice to bloat your game with too much treasure or deprive it of the same. Random magic item placement should always be tempered with good common sense by the GM.