In the code, Tiamat requires S+ rating overall with S+ empathy/pet, A+ maid/nurse/alchemy/witchcraft/painting, B+ xeno. The text asks for singing, not for painting, so that is a bug.
We can negate the negative mood if you manage to catch the fiend and have a place to put it.
When bored, positive moods end faster. If the day is ended with the master in a good enough mood, the master will not be bored the next day even if they have not been entertained for a long time. How tolerant the slaver is of not being entertained depends on slaver's brand reputation. We should perhaps make it depend on the personality attribute. But regardless of that, it's a comparison of how long since the last "good enough" entertainment (and the master's standards for "good enough" entertainment also rise as reputation increases) to the master's reputation and mood. If the sum of reputation and negative mood exceeds the time since the last good entertainment, the master will be bored. At the low end, assuming no recent entertainment, a Pessimistic or better mood will not be bored at F- brand reputation, but a Calm mood will be bored at D- brand reputation, a Hopeful mood will be bored at C- reputation, an Optimistic mood will be bored at B+ reputation, a Pleased mood will be bored at A+ reputation, and an Euphoric mood will be bored at S+ reputation. The master will never be bored if the day ends in Ecstatic mood. Drinking can elevate mood, so yes, it can help. In moderation. In terms of ways to obtain "good enough" entertainment (which reduces the mood threshold to avoid boredom), "serve me" performances qualify if done well. As you noted, going to watch arena events, socializing at the club, or going to the theater (slave reward) also qualify. At S+ brand reputation, the arena events only satisfy for a couple of days. The club and the theater last for a few days regardless of reputation, but they still interact with the slaver's mood as described, so you get some leeway but still need to keep mood up to avoid boredom.
We should probably make winning at arena events give the same "had a good time" entertained mood that you get for watching the arena events.
When you fail to cast Cruciato, the slave sees that you tried to punish her but failed and so the guilt goes away because it has been "dealt with" - in the sense that the slave becomes happier and less fearful while losing some obedience.
With Delikacia, the slave feels good about their ability to resist your magic, but also still feels that they earned a reward that has not yet been given.
In the dungeon, how much of the cookies the slave eats depends on their willpower, their pride and their mood. A bad mood of course results in eating more. Conversely, a good mood results in eating less. If the slave is young, Ecstatic and has B+ nature and S+ pride (unashamed), they will have 100 calories in the morning. Lolis eat less, so the same slave they'd start the day with zero. Mature slaves eat a bit more and would have an extra 100 calories. With S+ nature/pride/mood, calories can actually be negative for a loli (-100 is still considered "eating enough" not to starve - or even lose weight, unless the slave has a powerful metabolism). The cookies are specifically made to fatten the slave, so even if not many are eaten, the slave's physique will still rise over time. If they eat more, it will rise faster. Each time the slave's physique level goes up, or every so often if the slave is already at max physique, there is a chance that the slave's nature and pride will drop by a full level. So keeping a slave in the prison eating cookies can over time lower nature and pride to the lowest level. If the slave's temperament isn't at least B+, that would mindbreak them.
Dungeon is not an ideal place to keep a slave if you're not trying to punish them. It is especially unkind to slaves with high empathy, but sleeping in the dungeon (either by being placed there or with the sleep rule) induces despair in any slave who does not feel that they deserved punishment (less than 3 guilt). Unless they're the rare sort that enjoys being confined ("loves helplessness"). On the other hand, sleeping in the dungeon passively raises fear and taming, and if they do feel guilty, it also raises awareness. So, if a slave has 5 guilt, it can be convenient to put them in the dungeon for a few days.
The barn lets you keep four slaves: a second assistant (farmhand) once devoted enough, and you can also retrieve the cow, egglayer and pig. Combined with slave and assistant, this gives you six slaves every day with refreshed energy that you can train. Adding the dungeon makes seven.
