Beneath the City of Keys

A OnceWas RPG Adventure for Characters Level 5-6

Realm's End, the City of Keys, is in chaos. A wererat plague spreads through the sewers beneath the cobblestone streets, transforming victims into ravenous monsters with each passing full moon. Three city councilors lie dead. Districts fall one by one. The City Watch's assault failed catastrophically, leaving only two survivors—both driven mad by what they witnessed in the darkness below.

The party returns to the city bearing the Lamp of Yavanna, a divine artifact capable of curing lycanthropy with its holy light. But the sewers beneath Realm's End are no simple dungeon. Six rival factions vie for control: the Thieves' Guild fights to maintain its territory, pirates smuggle contraband through flooded passages, a hidden black market thrives in the darkness, and the Temple of Mairon practices forbidden necromancy. At the center of it all sits Publius, the Rat King—once a wealthy nobleman, now a cunning lycanthrope building an empire of disease and transformation.

This is not a linear dungeon crawl. Every choice matters. Will the party ally with the Thieves' Guild or make enemies of the underworld? Can they navigate the Hidden Market's neutral ground without sparking violence? Should they show mercy to wererat victims or eliminate the threat without hesitation? The faction politics are as dangerous as the monsters—and far more unpredictable.

In the depths, the party will face the Rat King in his throne room, battle through his wererat warren, and potentially witness his desperate prayer to Sqirthul, the Rat God. The Lamp of Yavanna may be powerful, but the wererats are adapting—and the conspiracy runs deeper than anyone suspects. Dark forces stir in the shadows, and the Rat King may be merely a pawn in a much larger, more sinister game.

What's Inside:

• A non-linear, faction-heavy adventure for 4-5 sessions of 3-4 hours each
• 35 keyed locations including the Wererat Warren, Hidden Market, High Point wizard tower, and Temple of Mairon
• 6 rival factions with detailed reputation mechanics and political consequences
• Epic boss battle with The Rat King featuring 3 dramatic phases
• Memorable NPCs: Mr. Lucan the assassin, FishBelly the mad poet, Black Hammond the market keeper, and Mac Luchna the death priest
• Detailed encounter scaling for parties of 3-7 players and levels 3-8
• Comprehensive GM guidance including session breakdowns, NPC roleplaying tips, and troubleshooting common scenarios
• Multiple paths to victory through combat, diplomacy, stealth, or clever faction manipulation
• Moral complexity and meaningful choices with lasting campaign consequences
• Connections to the larger OnceWas campaign storyline including hooks to future adventures

Requirements:

This adventure requires the OnceWas Core Rulebook and is designed for characters of 5th-6th level. The adventure can be adapted for 3rd-8th level parties with the provided scaling guidelines.

Part of the Odd Company Chronicles:

This adventure continues the storyline from A5: Silvandor and the Shattered Light, where the party acquired the Lamp of Yavanna. The events of this adventure set the stage for the climactic confrontation in A7 _Decent into Drell’s Mines. X1_Realm's End, the City of Keys is also recommended. Can be played as a standalone adventure or as part of the complete Odd Company campaign arc.

The rats are only the beginning. Something far darker stirs in the depths beneath the City of Keys.