When the anomaly collapsed for green codex in the lp, the big reward was 6 perfect gals, and a good ship weapon with infinite ammo (that was sadly lost almost immediately).
For the gray codex, you get the following:
And also the conversion launcher ship weapon.
This is a very strong weapon... but you get 7 shots total from the collapse, and nothing early on has shields (and when you do encounter shielded targets 90*7*2 total damage in a weapon slot isn't actually that good either, and they fire real slow).
As for the codex rewards themselves... they're all about research. Data discs give you cheap research rolls, especially once you've cleared out the first 400 possible results. Gnome can be repeatedly interrogated for various things. The real prize is the liber occultus and book of witchcraft. We saw the liber in the lp, as a rare drop. Getting one early doesn't help so much, as it needs to be combined with a church reverend to unlock things... unless you are gray. Because the book of witchcraft substitutes for half of the translated libers unlocks, and gives instant access to researching voodoo. The alternatives being either the liber or interrogating a mage unit of some variety.
But voodoo is also a lategame thing, so getting it early doesn't unlock much iirc. I think you can research the wands and find out their stats? However, progressing this line and researching hyper-wave mysticism does unlock the Astrosensorium, which is pretty great.
For something you can get relatively early, 3 brainers in one slot is amazing value. You can't spam it everywhere due to the 333 glamour cost, but it's still a good boost to your midgame research speed.
Slightly longer down this early voodoo line (early voodoo still means deep midgame), requiring force circuitry (get from high tier church members) and some random esoteric lore (pray for decent rng) you get arguably the biggest thing for gray codex: muscle mages. Muscle magic is cast via a spellbook, and scales about 50/50 with strength and voodoo mastery. So it's magic for ubers, because they're the only ones with good strength and voodoo power and voodoo skill.
which unlocks the minx armor and gray spellbook (requires back to school as well).
The gray spellbok doesn't really explain itself (and took me a while to figure out): it basically functions like a gun that can accept 3 different types of ammo: quick spell, power spell, complex spell. Quick spells fire bursts of 3 for 33 TUs and 2 fresh, power spells fire arcing bursts of 5 for 66 TUs and 3 freshness and complex spells are single shot for 77 TUs and 3 fresh. Of particular value is that the spellbook and all spells are shadowlands (and 0-g) compatible, allowing for a reliable ranged option. Although that's way in the future from when you get it. Spells also only cost hellerium (and a bit of money) to manufacture. Spells are researched separately, so early on you have basic spells embers of pyrome, ashes of babylon, spectral hand and mind knives. Spell scrolls take up 2x2 slots, and there's no way to unload a specific scroll, so you're very limited with both reloads (3 shots for complex, ~10 bursts for power and quick) and changing ammo (bring a second book instead).
It's not kidding when it says its only use is illumination, and even then... I'd prefer just throwing a molotov or something that glows?
It's also inaccurate as fuck.
None of these are super amazing, although mind knives are an early source of mind damage, but in practice I didn't find any early uses for them (late uses however...). Even with 130 strength, they aren't actually very good with low voodoo mastery, and it takes a long time to train voodoo skill to get good mastery, as it's power*skill.
When you understand zombie brains you get bone fever. Don't let the 0 fool you, it scales, and things that are vulnerable to anti-E damage tend to have crazy multipliers.
Understanding optronics gets you Circuit breaker. Emp is a rare damage type, especially in direct fire form, so this one can be really good against terminators and other robot types.
Probably the most generally useful spells is unlocked with captains log #2, spectral eye. It spawns a flying unit that scouts really well, which is always useful.
Really lategame, with proper voodoo schools founded, you get access to some final spells.
Contact with the god of the dead you get shades of verdan (sic).
Voodoo: Excess gets tears of gomorrah (ranged charm damage is very rare, ignores all shields).
Voodoo Destruction gives shieldbuster, but in practice I found this to be utterly useless compared to actual anti-shield tactics. It doesn't deal nearly enough damage per tu.
Knowledge of entropomancy gives the final spell, hellgate. Reliable ranged warp damage can really wreck anything with red armor (hello marsec), so this is prety good, although the high TU cost can be pretty brutal for retaliations.
And finally an example of damage scaling (they're basically all like this, maybe adjust 30-50% down for the power/quick spells).
All told, the spellbook is not very high power. What it is is a toolbox. It has a convenient source of basically every exotic damage type (except bio, I am very jelly of the tentacles green codex gets that we saw in the lp). And sometimes a toolbox is what you need. As for spells of pure destructive potential, stick around.
That seems like enough content for one part though.
/SPOILER]
