The latest development blog on the Frayed Knights sequel deals with spells, and how they will be approached in the title compared to the original. So, here's how it's going to work:
#1 Spellcasters (who can, as in the first game, be anybody, with the right feats) have two sets of spells: A spellbook, and an active spell list. You can only cast spells from the active spell list, and it can only be changed outside of combat. The size of the active spell list is TBD, but it's small enough to be hotkeyed for that character. We're not sure yet if there'll be a limit to the number of spells a player can have in their spellbook, but there probably will be a (large) limit, with the ability to delete non-core spells to make room for more. Anyway the upshot is this: You'll need to be selective about spell choices, but you won't have to wade through several layers of menus just to cast a common spell again.
#2 The four spellcasting categories (Sorcerer, Nature, Divine, Profane) all have different specializations, strengths, and weaknesses. This was kinda-sorta present in FK1 as loose guidelines, but they are going to be more solidly coded in the sequels. Each spellcasting category has certain effects that are its specialties, which really define the category (like straight-up healing for Divine casters, or direct damage for sorcerers). Then there are spells effects which are secondary to the class, and weaker than the specialties by level. Then there's the tertiary spell effects which are pretty weak, but can do in a pinch. Finally, there are spell effects that are simply not available for that spellcasting category like healing for sorcerers.
#3 There are a few (core) spells for a spellcasting category that are automatically available. The (common) spells of FK1 would be like this. These can't be erased from spellbooks, and technically you COULD win the game with these spells and nothing else, but you'd be making things a lot harder on yourself. Unlike FK1, these will be few and far behind. Don't expect a new spell every level.
#4 Then there are some (signature) spells for Frayed Knights which are custom, hand-built spells with unique effects or amusing visuals. These are generally not (core,) but aren't hard to find. They are either plot-critical / utility spells (not sure if we'll have these in game 2), or they'll be deliberately overpowered but expensive to cast. Power Word: Defenestrate belongs here, but it will be slightly beefed up. There will be others of similar amusing variations here. Some may even violate the usual specializations from point 1.
#5 THIS IS THE BIG ONE The game will provide lots of procedurally generated spells throughout the game. Some will be available in a shop, others can be found on scrolls throughout the game. Scrolls can be used to either scribe a spell in your spellbook, or cast directly. These will be random, so the exact spells available to you will be different with every game. Because of the fixed, custom spells from points 3 and 4, you won't be left high-and-dry without any spells to fulfill a caster's primary role, but you may have to make due with some interesting combinations you've found by chance.
So there you go: Prepare to drown in spells in Frayed Knights 2.
This isn't a huge deviation from what I did in FK1, where I generated dozens and dozens of spells using a formula as a guide, and some rules-of-thumb for variation. Now, I just have to let the computer use the formula and rules-of-thumb to procedurally create the spells. And then there's the naming. Spell names should be interesting. But anyway, the end result is that spells will act a little like weapons & armor in Diablo-style games. They'll be more-or-less balanced, offer some occasionally weird mixes of combo-effects (a spell that does fire damage and puts you to sleep? I guess it could happen.), and may range from the broadly useful to the highly specific-use. Hopefully it flies.