D&D5e Downtime

Player's Handbook

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Crafting: Creating items and goods.
Practicing a Profession: Working for another, for which you are paid.
Recuperating: Recovering from poison, illnesses, or lingering injuries.
Training: Learning new Skills (500 days), Tool Proficiencies (250 days), or Languages (250•125•80 days)

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Building a Stronghold: Constructing a building (must own land)
Carousing: Partying and gambling.
Crafting a Magic Item: Creating an item of magic (must have schema)
Gaining Renown: Working for your Faction to gain Rank.
Performing Sacred Rites: Performing and observing religious rites to gain Hero Points.
Selling Magic Items: Finding a buyer for a magic item.
Sowing Rumors: Creating new rumors and spreading them around town.

Establish Information Network: Establishing an information network.
Utilize Information Network: Using an established information network.
Research: Researching Lore (knowledge and information), Formulae (spells), and Schema ("recipes" for making magic items).
Establishing or Running a Business: Running a business that might result in profits or could cost you.