diff --git a/playbill/spires/methods/gourmond.yaml b/playbill/spires/methods/gourmond.yaml
index eedafaa..ba16391 100644
--- a/playbill/spires/methods/gourmond.yaml
+++ b/playbill/spires/methods/gourmond.yaml
@@ -4,6 +4,7 @@ name: Gourmond
 curator: TBD
 abilities:
   - [identify-poison, neutralize-poison]
+  - [camp-food]
 description: Your prowess in cooking is second only to your prowess in eating.
 ---
 $define: ability
@@ -21,7 +22,6 @@ banes:
 description: |-
   Focus your senses on a food or drink to determine if it is poisoned.
 
-  {dmg:1,magic}
   You can also identify the type of poison used.
 ---
 $define: ability
@@ -29,10 +29,16 @@ id: neutralize-poison
 name: Neutralize Poison
 type: action
 roll: cunning
-description: Neutralize a poison by adding an ingredient known to render the poison inert
+description: Neutralize a poison detected using {ability:identify-poison} by adding an ingredient known to render the poison inert
 boons:
   - You manage to neutralize the poison without drawing any attention
   - You are able to also neutralize poisons in the food of your party members
 banes:
   - You are not able to fully neutralize the poison, only weakening the effects
   - Someone catches on to you
+---
+$define: ability
+id: camp-food
+name: Camp Food
+type: trait
+description: Regain an additional {stat:hp,2} when you {rule:regroup}
diff --git a/playbill/spires/rules/regroup.yaml b/playbill/spires/rules/regroup.yaml
new file mode 100644
index 0000000..335bf0b
--- /dev/null
+++ b/playbill/spires/rules/regroup.yaml
@@ -0,0 +1,4 @@
+$define: rule
+id: regroup
+name: Regroup
+description: Regain some hp by resting
diff --git a/src/index.ts b/src/index.ts
index 161608a..dfeff05 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,164 +1,211 @@
-import chalk from "chalk";
 import { parseArgs } from "node:util";
+import chalk from "chalk";
 import { loadBindingFile } from "./binding";
+import { DirectiveError, processLang } from "./lang";
 import {
   type AnyResource,
   ValidatedPlaybillSchema,
   getEmptyPlaybill,
 } from "./playbill-schema";
 import { loadResourceFile } from "./resource";
-import { version } from "../package.json" with { type: "json" };
+import { usage } from "./usage";
 
-const { values: options, positionals: args } = parseArgs({
-  args: Bun.argv.slice(2),
-  options: {
-    write: {
-      short: "w",
-      type: "boolean",
-      default: false,
-    },
-    check: {
-      short: "c",
-      type: "boolean",
-      default: false,
-    },
-    outfile: {
-      short: "o",
-      type: "string",
-      default: "playbill.json",
-    },
-    help: {
-      short: "h",
-      default: false,
-      type: "boolean",
-    },
-    verbose: {
-      short: "v",
-      default: false,
-      type: "boolean",
-    },
-  },
-  strict: true,
-  allowPositionals: true,
-});
+class CLIError extends Error { }
 
-if (args.length === 0 || options.help) {
-  console.log(`${chalk.bold("muse")} - Compile and validate Playbills for Proscenium
-${chalk.dim(`v${version}`)}
+async function main(): Promise<boolean> {
+  // Parse command line arguments
+  const { values: options, positionals: args } = parseArgs({
+    args: Bun.argv.slice(2),
+    options: {
+      write: {
+        short: "w",
+        type: "boolean",
+        default: false,
+      },
+      check: {
+        short: "c",
+        type: "boolean",
+        default: false,
+      },
+      outfile: {
+        short: "o",
+        type: "string",
+        default: "playbill.json",
+      },
+      help: {
+        short: "h",
+        default: false,
+        type: "boolean",
+      },
+      verbose: {
+        short: "v",
+        default: false,
+        type: "boolean",
+      },
+      minify: {
+        short: "m",
+        default: false,
+        type: "boolean",
+      },
+    },
+    strict: true,
+    allowPositionals: true,
+  });
 
-Usage:
-  muse [/path/to/binding.yaml] <options>
+  if (options.help) {
+    console.log(usage);
+    return true;
+  }
 
-Options:
-  --check         Only load and check the current binding and resources, but do not compile
-  --write         Write the output to a file. If not specified, outputs to stdout
-  --outfile       Specify the output file path [default: playbill.json]
-  --verbose, -v   Verbose output
-  --help, -h      Show this help message
-`);
-  process.exit(0);
+  if (options.check && options.write) {
+    throw new CLIError("Cannot use --check and --write together");
+  }
+
+  const VERBOSE = options.verbose;
+
+  /**
+   * Log a message if the vervose flag has been set
+   * @param msg - The message to log
+   */
+  function v(msg: string) {
+    if (VERBOSE) {
+      console.log(chalk.dim(msg));
+    }
+  }
+
+  const bindingPath = args[0] ?? "./binding.yaml";
+
+  v(`Building Playbill with binding: ${bindingPath}`);
+
+  // Check if the binding file exists
+  const bindingFileCheck = Bun.file(bindingPath);
+  const bindingFileExists = await bindingFileCheck.exists();
+
+  if (!bindingFileExists) {
+    throw new Error(`Binding file not found: ${bindingPath}`);
+  }
+
+  const binding = await loadBindingFile(bindingPath);
+
+  v(`↳ Binding loaded with ${binding.files.length} associated resources`);
+
+  const loadedResources: AnyResource[] = [];
+
+  v("Loading resources");
+
+  // Load resources listed in the binding file
+  for (const filepath of binding.files) {
+    v(`↳ Loading ${filepath}`);
+    const loaded = await loadResourceFile(filepath);
+    v(`  ↳ Loaded ${loaded.length} resources`);
+    loadedResources.push(...loaded);
+  }
+
+  v("Constructing playbill");
+
+  // Consjtruct the playbill object
+  const playbill = getEmptyPlaybill();
+
+  playbill.id = binding.info.id;
+  playbill.name = binding.info.name;
+  playbill.author = binding.info.author ?? "Anonymous";
+  playbill.version = binding.info.version;
+
+  for (const resource of loadedResources) {
+    switch (resource.$define) {
+      case "ability":
+        playbill.abilities.push(resource);
+        break;
+      case "species":
+        playbill.species.push(resource);
+        break;
+      case "entity":
+        playbill.entities.push(resource);
+        break;
+      case "item":
+        playbill.items.push(resource);
+        break;
+      case "tag":
+        playbill.tags.push(resource);
+        break;
+      case "method":
+        playbill.methods.push(resource);
+        break;
+      case "lore":
+        playbill.lore.push(resource);
+        break;
+      case "rule":
+        playbill.rules.push(resource);
+        break;
+      case "playbill":
+        throw new Error("Cannot load playbills rn dawg");
+    }
+  }
+
+  // Evaluate directives in descriptions for all resources
+  v("Processing descriptions");
+  for (const resource of loadedResources) {
+    try {
+      resource.description = await processLang(resource.description, playbill);
+    } catch (error) {
+      if (error instanceof DirectiveError) {
+        console.error(
+          `Error processing directives in ${resource.$define}/${resource.id}`,
+        );
+        console.error(error.message);
+      } else {
+        console.error(error);
+      }
+      return false;
+    }
+  }
+
+  // Validate the playbill object
+  v("Validating playbill");
+  const validatedPlaybill = ValidatedPlaybillSchema.safeParse(playbill);
+
+  if (!validatedPlaybill.success) {
+    console.error("Error validating playbill");
+    console.error(validatedPlaybill.error.errors);
+    return false;
+  }
+
+  v("Playbill validated");
+
+  // If --check is set, exit here
+  if (options.check) {
+    console.log(chalk.green("Playbill validated successfully"));
+    return true;
+  }
+
+  const finalizedPlaybill = JSON.stringify(
+    validatedPlaybill.data,
+    null,
+    options.minify ? undefined : 2,
+  );
+  if (options.write) {
+    await Bun.write(options.outfile, finalizedPlaybill);
+    return true;
+  }
+
+  console.log(finalizedPlaybill);
+  return true;
 }
 
-if (options.check && options.write) {
-  console.error("Cannot use --check and --write together");
+try {
+  const success = await main();
+  if (success) {
+    process.exit(0);
+  } else {
+    process.exit(1);
+  }
+} catch (error) {
+  if (error instanceof Error) {
+    console.error(chalk.red(error.message));
+  } else {
+    console.error("An unknown error occurred");
+    console.error(error);
+  }
+
   process.exit(1);
 }
-
-const VERBOSE = options.verbose;
-
-function verboseLog(msg: string) {
-  if (VERBOSE) {
-    console.log(chalk.dim(msg));
-  }
-}
-
-const bindingPath = args[0] ?? "./binding.yaml";
-
-verboseLog(`Using binding file: ${bindingPath}`);
-
-// Check if the binding file exists
-const bindingFileCheck = Bun.file(bindingPath);
-const bindingFileExists = await bindingFileCheck.exists();
-
-if (!bindingFileExists) {
-  console.error(`Binding file not found: ${bindingPath}`);
-  process.exit(1);
-}
-
-verboseLog("↳ Binding file found");
-
-const binding = await loadBindingFile(bindingPath);
-
-verboseLog(
-  `↳ Binding loaded with ${binding.files.length} associated resources`,
-);
-
-const loadedResources: AnyResource[] = [];
-
-verboseLog("Loading resources");
-
-// Load resources listed in the binding file
-for (const filepath of binding.files) {
-  verboseLog(`↳ Loading ${filepath}...`);
-  const loaded = await loadResourceFile(filepath);
-  verboseLog(`  ↳ ${filepath} loaded with ${loaded.length} resources`);
-  loadedResources.push(...loaded);
-}
-
-verboseLog("Constructing playbill");
-
-// Consjtruct the playbill object
-const playbill = getEmptyPlaybill();
-
-playbill.id = binding.info.id;
-playbill.name = binding.info.name;
-playbill.author = binding.info.author ?? "Anonymous";
-playbill.version = binding.info.version;
-
-for (const resource of loadedResources) {
-  switch (resource.$define) {
-    case "ability":
-      playbill.abilities.push(resource);
-      break;
-    case "species":
-      playbill.species.push(resource);
-      break;
-    case "entity":
-      playbill.entities.push(resource);
-      break;
-    case "item":
-      playbill.items.push(resource);
-      break;
-    case "tag":
-      playbill.tags.push(resource);
-      break;
-    case "method":
-      playbill.methods.push(resource);
-      break;
-    case "lore":
-      playbill.lore.push(resource);
-      break;
-    case "rule":
-      playbill.rules.push(resource);
-      break;
-    case "playbill":
-      throw new Error("Cannot load playbills rn dawg");
-  }
-}
-
-verboseLog("Validating playbill");
-
-// Validate the playbill object
-const validatedPlaybill = ValidatedPlaybillSchema.parse(playbill);
-
-verboseLog("Playbill validated");
-
-if (options.write) {
-  await Bun.write(options.outfile, JSON.stringify(validatedPlaybill, null, 2));
-} else if (!options.check) {
-  console.log(validatedPlaybill);
-}
-
-if (options.check) {
-  console.log(chalk.green("Playbill validated successfully"));
-}
diff --git a/src/lang.ts b/src/lang.ts
index f31a6f9..58ba167 100644
--- a/src/lang.ts
+++ b/src/lang.ts
@@ -1,21 +1,74 @@
 import { z } from "zod";
+import { StatsSchema, type Playbill } from "./playbill-schema";
 
-const ALL_DIRECTIVES = ["dmg"] as const;
-const DirectiveSchema = z.enum(ALL_DIRECTIVES);
-type DirectiveName = (typeof ALL_DIRECTIVES)[number];
-type DirectiveHandler = (...args: string[]) => string;
+const DirectiveSchema = z.enum(["dmg", "ability", "stat", "rule"] as const);
+type DirectiveName = z.infer<typeof DirectiveSchema>;
+type DirectiveHandler = (playbill: Playbill, ...args: string[]) => string;
+
+export class DirectiveError extends Error { }
 
 const ProsceniumLangDirectives: Record<DirectiveName, DirectiveHandler> = {
-  dmg: (amount = "1", type = "physical") => {
-    return `<em class='dmg ${type}'>${amount}</em>`;
+  dmg: (_, amount = "1", type = "phy") => {
+    const DAMAGE_TYPES = ["phy", "arc", "physical", "arcane"];
+    if (!DAMAGE_TYPES.includes(type)) {
+      throw new DirectiveError(`Unknown damage type: ${type}`);
+    }
+
+    const finalizedType = type.slice(0, 3);
+    return `<em class='dmg ${finalizedType}'>${amount}</em>`;
+  },
+
+  ability: (playbill: Playbill, ref: string) => {
+    if (typeof ref !== "string") {
+      throw new DirectiveError("Invalid ability reference");
+    }
+
+    const foundAbility = playbill.abilities.find((a) => a.id === ref);
+
+    if (foundAbility === undefined) {
+      throw new DirectiveError(`Unknown ability reference: ${ref}`);
+    }
+
+    return `<em class="ref-ability">${foundAbility.name}</em>`;
+  },
+
+  rule: (playbill: Playbill, ref: string) => {
+    if (typeof ref !== "string") {
+      throw new DirectiveError("Invalid rule reference");
+    }
+
+    const foundRule = playbill.rules.find((r) => r.id === ref);
+
+    if (foundRule === undefined) {
+      throw new DirectiveError(`Unknown ability reference: ${ref}`);
+    }
+
+    return `<em class="ref-rule">${foundRule.name}</em>`;
+  },
+  stat: (_, stat: string, amount = "") => {
+    const lower = stat.toLowerCase();
+    const parsed = StatsSchema.safeParse(lower);
+
+    if (!parsed.success) {
+      throw new DirectiveError(`Unknown stat: ${stat}`);
+    }
+
+    if (amount !== "") {
+      const amountAsNum = Number.parseInt(amount, 10);
+      if (Number.isNaN(amountAsNum)) {
+        throw new DirectiveError(`Invalid amount: ${amount}`);
+      }
+      return `<em class="stat">${amount} ${stat.toUpperCase()}</em>`;
+    }
+
+    return `<em class="stat">${stat.toUpperCase()}</em>`;
   },
 };
 
-function processCommands(text: string): string {
+function processCommands(text: string, playbill: Playbill): string {
   const commandPattern = /\{(\w+):([^}]+)\}/g;
 
   return text.replace(commandPattern, (_match, command, args) => {
-    // TODO: Improve error reporting
     const directive = DirectiveSchema.parse(command);
     const handler = ProsceniumLangDirectives[directive];
     const parsedArgs = [];
@@ -35,15 +88,18 @@ function processCommands(text: string): string {
     }
     parsedArgs.push(currentArg.trim().replace(/^"|"$/g, ""));
 
-    return handler(...parsedArgs);
+    return handler(playbill, ...parsedArgs);
   });
 }
 
-export async function processLang(input: string): Promise<string> {
+export async function processLang(
+  input: string,
+  playbill: Playbill,
+): Promise<string> {
   const lines = input.split("\n");
   const processedLines: string[] = [];
   for (const line of lines) {
-    const processed = processCommands(line);
+    const processed = processCommands(line, playbill);
     processedLines.push(processed);
   }
 
diff --git a/src/playbill-schema.ts b/src/playbill-schema.ts
index eb480de..2412eea 100644
--- a/src/playbill-schema.ts
+++ b/src/playbill-schema.ts
@@ -1,4 +1,4 @@
-import { type ZodSchema, z } from "zod";
+import { z } from "zod";
 
 /*
  * TYPE          REFERENCES
@@ -309,7 +309,7 @@ export const ValidatedPlaybillSchema = PlaybillSchema.superRefine(
 export type Playbill = z.infer<typeof PlaybillSchema>;
 export type ValidatedPlaybill = z.infer<typeof ValidatedPlaybillSchema>;
 
-export const ResourceMap: Record<ResourceType, ZodSchema> = {
+export const ResourceMap = {
   ability: AbilitySchema,
   species: SpeciesSchema,
   entity: EntitySchema,
@@ -319,7 +319,7 @@ export const ResourceMap: Record<ResourceType, ZodSchema> = {
   lore: LoreSchema,
   rule: RuleSchema,
   playbill: PlaybillSchema,
-};
+} as const;
 
 export const AnyResourceSchema = z.discriminatedUnion("$define", [
   AbilitySchema,
diff --git a/src/resource.ts b/src/resource.ts
index 82c3147..8b7e6f2 100644
--- a/src/resource.ts
+++ b/src/resource.ts
@@ -8,6 +8,14 @@ import {
 export class ResourceFileError extends Error { }
 export class NullResourceError extends Error { }
 
+/**
+ * Load and process all documents in a yaml file at the given path
+ * @param filePath - The path to the yaml file
+ * @returns An array of validated resources
+ *
+ * @throws ResourceFileError
+ * @throws NullResourceError
+ */
 export async function loadResourceFile(
   filePath: string,
 ): Promise<AnyResource[]> {
@@ -37,8 +45,8 @@ export async function loadResourceFile(
     const parsed = AnyResourceSchema.parse(raw);
     const type = parsed.$define;
     const schemaToUse = ResourceMap[type];
-
-    collection.push(schemaToUse.parse(parsed));
+    const validated = schemaToUse.parse(parsed);
+    collection.push(validated);
   }
 
   return collection;
diff --git a/src/usage.ts b/src/usage.ts
new file mode 100644
index 0000000..dd339ae
--- /dev/null
+++ b/src/usage.ts
@@ -0,0 +1,17 @@
+import { version } from "../package.json" with { type: "json" };
+import chalk from "chalk";
+
+export const usage = `
+${chalk.bold("muse")} - Compile and validate Playbills for Proscenium
+${chalk.dim(`v${version}`)}
+
+Usage:
+  muse [/path/to/binding.yaml] <options>
+
+Options:
+  --check         Only load and check the current binding and resources, but do not compile
+  --write         Write the output to a file. If not specified, outputs to stdout
+  --outfile       Specify the output file path [default: playbill.json]
+  --verbose, -v   Verbose output
+  --help, -h      Show this help message
+`.trim();