Downtime activities are done between sessions. They are resolved at the beginning of each session. You may choose 1 activity at the start of each session, as well as any number of free actions. The following options are available and described below:
Carousing
Wager any amount of d6s up to your HD. Pay GP equal to amount rolled*20. Receive 5 XP for every 1 gold paid. If you can’t pay it off, you require a loan from another player or are now in debt. Afterwards, the character must make a saving throw (-4 penalty if in debt). The saving throw is to complete the carousing without unexpected consequences.
Contemplation
Clerics and philosophers may spend time in contemplation on a specific question or problem. There is a 1-in-6 chance of receiving divine inspiration from the cosmos. For every 1000gp spent, the chance increases by an additional 1-in-6.
Level Training
A character continues to the next level through study with a suitable trainer. The trainer must typically be at least two levels higher than them. The training costs 100gp per current level of the character.
Hospital Rest
Spend time recovering from diseases and major ailments. Healing is increased from 1 to a rate of 1d3 HP per day.
Investigation
Ask one question that you spend a week investigating the answer to. The chance of success is dependent on the difficulty of the question, the means taken, and the funding spent in securing an answer to the question.
Plagiarism
Thieves may spend time plagiarizing a found manuscript or ancient text into a new work. In order to do so, they must roll against their plagiarism skill. Success indicates that they may pass the work off as their own, either through selling their ideas for profit or increasing their scholarly profile.
Spell Scribing
Spend time copying a scroll into a spellbook. After spending the time and money, the character rolls their Chance to Know Spell. If they fail, they do not learn the spell, and cannot forever, except when using a Wish.
Research Cost: 100gp per spell level if scribing from a scroll.
Training
Spend time training a new skill or ability with a qualified instructor. The benefit and cost depends on the skill studied.
Example skills: psychoanalysis, demonology, geometry, abstract art, geology, music, metallurgy, war machines, sorcery, rootcraft, astronomy, flight
Credit to Justin H who I stole a lot of this from.