I like to use the weird spells that players rarely take due to being less than optimal. That way they still get to use them situationally, without having to "waste" a slot.

The exception is when there's a particular story reason for a certain type of item to crop up; for instance, a group of assassins hunting a powerful mage might have a lot of dispel and antimagic type things.

If I'm doing it out of the kindness of my heart (aka the players are taking way too long to solve what should be a relatively easy problem and I'm getting impatient), I'll give them exactly what they need to get through the problem.

I usually would have things pre-placed in advance. Especially if they are going to be needed for something and there's a chance a party member wouldn't have the skill/spell to do it. But that doesn't always mean the players will find it or even look for it.

If it's just random loot time, I use the tables and roll dice for it.

I love to do spell scrolls in a three different ways that sometimes overlap. One is spells that fill a gap in their list which is usually very similar to spells that they ask for. I encourage asking for things so I can know but don't give them everything. This is similar to spells that would be useful for the current adventure or the next one.

The other are weird or very situationally useful spells because I want to see them in play. These are just things that no one would ever pick because they are situational. These are just fun to have especially if they get them from NPCs or dead enemies. These I give out more freely

The last are thematically appropriate spells. Doing a cold themed dungeon get ready for lots of cold damage spells or other similar spells. These are kind of fun because you can get some odd balls in there as well.

I guess I love weird spells.

I've got two methods for scrolls.

The first is "Don't bother with anything they are capable of casting by themselves." As in, I'll only drop scrolls of a higher rank than their top slots. The flashier the spell, the better.

The second is "The player is actively seeking this out in-character," in which case I'll just drop a cache of 4-8 of the spell at the end of a mini-quest performed alongside whatever the current job is.

I've got one method for wands.

Is the spell something with a persistent effect? Then bam. There you go. I'll never drop a wand that loses its utility as soon as you spend the actions, or worse, as you level up. Spells like fireball are a no-go, but spells like Shape Stone are great.

And as for staves, I've got two again.

One, does the staff have a good evergreen first level spell (or more) like Illusory Object or Heal? Then it's going into the loot piles.

And two, is there a thematic link I can make to where the staff is found? That's a going on the baddies' fireplace mantle to sell their aesthetic.

It’s something I’m thinking about right now because I’m in the middle of thinking about giving out one as I write this.

The factors I’m thinking about are things like: finding a good spell that helps promote teamwork, because I think the strength of teamwork is something I really value about Pathfinder but find my players don’t go for it as much as I’d like. So the item should hopefully nudge them a little in the right direction. I’m also thinking about things that might be thematically appropriate for where they’re getting the scroll from. And finally, I also want something that’s going to feel fun and powerful in our campaign, without completely trivialising an encounter that’s meant to be difficult.

Same question I had when it comes to "gifting" alchemical formulae to my alchemist at the table.

I filtered the list of recipes by the level of the source, which is a NPC. Then I rolled 5 times for commons and once for an uncommon.

That's the formulas my alchemist was able to learn from.

And as I know that the player of that alchemist is a tinker, they will find a use and or edge case for any of them. So nothing goes to waste.

I imported the JSON files from the Foundry VTT module into a Pandas dataframe in Python and randomly select from there, using the party's casting rank +1 as an upper limit.

RNGesus.