The Four Key Resources
Player Characters in Dungeons and Dragons have Four Key Resources, and understanding their economic interactions is key for deciding how to press characters into making decisions. So often I hear DMs complaining that their party is bored or that they the find the content too easy, or that they don't know how to make something challenging. It usually comes back to mismanagement of these Four Key Resources and their bound economy. The resources, to list, are: HP, Ability Slots, Gold, and Time. Tension exists as a result of these resources, and as a result of what the PCs can do with them.
I've mentioned before about how PCs are inherently agents of change, and these resources relate directly to the amount of change they can bring to bear, and upon who they can force that change. These resources are what increase when PCs gain levels, and they empower PCs of higher levels to conduct bigger changers upon more powerful actors as they progress through the tiers. Finally, they work on an economy between each other, which is where DMs often become unstuck.
The Resources Themselves - Weapons of Change
Hit Points represent a character being alive. Obviously (or perhaps not) Characters must be alive in order to interact with the world. Hit Points, then, are a binary resource. You've either got 'em and so you can participate in Scenes; or you don't, and so you can't.
Ability Slots represent a character's ability to violate the core action economy (ah! he said it, he said it!) of the game. If we look at 1st level characters, they're doing around 1d10 damage per round. At 5th level most characters do around 2d10 damage per round. There's some small variability (including trade-off for secondary effects ala Ray of Frost having reduced damage for a slow), but these are exceptions that prove the rule. Characters can vastly outstrip this using Ability Slots. A fighter's Action Surge (1/short rest) can allow another 2 attacks at 5th level. A 5th level wizard who spends a 3rd level spell slot on fireball can change their per action damage from 2d10 (11 damage average) to 8d6 (28 damage average)!
Gold is a liquid resource. It does nothing on it's own, but (in most campaigns) it is easily invested into other resources. Gold is also specifically interesting because players must be proactive with their allocation. It's rare to buy Potions of Healing in the dungeon, for example.
Time. Time is the most mismanaged resource from a DM's perspective. This is specifically the time within the world, not your play time at the table. Within the game, everything takes time. Travel, Big Bad Evil Guy's machinations, even the PCs actions from an 8 hour long rest, right down to taking an action to cast a spell or swing a sword. This is what action economy really means. Time can exist in a binary sense (The Party arrives either Just In Time or Just Too Late), or it can exist in a scaling sense such as the amount of time your Impending Doom will take to arrive (and how bad things get along the way).
The Resource Economy
If players need more HP:
- Ability Slots can be traded for HP through Spells (Healing Word) or Spell-like Abilities (Second Wind). Note there is no cantrip that heals, nor medicine check. This is important. HP costs something to regain.
- Gold can be spent on Potions of Healing to trade directly for HP. Also through the purchase of gear (AC), Gold can prevent HP loss.
- Time can be traded for HP through Rests.
If players need more Ability Slots:
- HP is an interesting trade for Ability Slots. It is based on the concept that players are action limited (ie you can only do a certain amount of actions on your turn) to allow Baddies the chance to respond. So instead of using big powerful Ability Slots that end the fight earlier, PCs can extend the combat encounter out by doing only their regular amount of damage. The extra length of the combat results in more HP damage taken. An interesting round-a-bout trade.
- Gold can allow more reliable use of Ability Slots (+1 weapons and focii), or by providing extra slots with different degrees of flexibility (wands or magic items with abilities).
- Time is traded to return Ability Slots through Rests.
If players need more Gold:
- HP is traded for Gold by going out and fighting monsters to steal their treasure.
- Ability Slots are traded for Gold by going out and fighting monsters to steal their treasure.
- Time can be traded for Gold through either the time spent finding the treasure, or time spent turning the gold from a liquid resource into the invested resource (time spent crafting a magic item, for example).
If players need more Time:
- HP is traded for Time by refusing to rest and spend those hit dice.
- Ability Slots are traded for Time by casting spells that either bypass encounters, or burn through encounters faster.
- Gold can be traded for Time by mostly in it's functions of saving the other resources. Buying faster travel methods too, if the scope covers a large geography.
Tension as a Result of Resource Economy
Players care, first and foremost, about their Character's survival and prosperity. About not only maintaining but increasing their ability to make things happen (change). In Dungeons and Dragons 5th Edition, we see this primarily in combat: Tension exists where Baddies demand players reduce their HP and, once that's low enough to demand a reaction, demand Ability Slots to either have PCs do more damage (to avoid further HP loss) or cast some healing magic. Alternatively the Baddie demands some gold is dropped on potions or other Spell-like Consumables. Combat exists purely as a race between HP values, with the other resources available as a trade. However, because HP is a binary resource there is no tension for a group of 5 clerics with 1hp each, while ever they have a fistful of healing potions and their daily allotment of healing spells. Similarly, a party with no spell slots remaining has no tension while ever they all have near-max HP and bags full of alchemist's fire.
Tools to Take Away
This is such an important point that I'll be discussing the tools, the methods, in the next post. Specifically, the next post will cover structuring encounters to target specific resources, and more importantly how to threaten PCs outside of combat. For now, be aware that PCs view your world through their ability to change it. This means that tension is relative. A fully stocked and rested party facing down Venomfang will not initially experience tension (it will come as they burn through resources!), however a fully depleted party trying to talk their way past 3 goblins may feel the pucker as soon as you call for initiative.