What does casting spells involve?

Initial assumption: you can cast spells with just your mind

The only thing we know is from the rules is that you can use an ingredient to increase the power of your spell. But the rules don’t tell us how. And they don’t tell us what else could be involved, except by process of elimination.

Symbolism tells us that that a sorcerer needs a free hand to shape symbols in the air if they don’t have any pre-prepared. Ergo, non-Symbolism sorcerers and druids don’t need to do any hand movements, so there’s no assumed somatic component in standard spells.

Similarly, there are a few power words, which are fast actions and presumably the action of the sorcerer saying “fzzot!” or something. I think it follows from there that you don’t need to say anything to cast a spell (although obviously calling your attacks has a certain appeal); in fact, given that there’s a druid stealth spell (Cat’s Paw), at least some times you explicitly shouldn’t say anything to cast the spell.

You must spend a fast action to ready your grimoire, but then you can cast a spell from your grimoire in exactly the same time as you’d be able to cast it from memory. So I think it therefore follows that you are not reading the spell from the grimoire, let alone speaking magic words as a result, but you merely have some kind of boost from some kind of pre-recorded “oh yeah, this is what the spell is all about” thing built into your grimoire.

How near/new do ingredients need to be?

There’s a bunch of things that you can burn up if you want your spell to be better. Piece of chalk, divining rod, piece of cloth, etc. - all sorts of tangible physical objects that are easy to have in a hand.

But Dispel magic is a reactive power word, and the ingredient is iron filings. Do you need to first have a handful of iron filings before you can cast the spell with a bonus, as a reaction? Or can you tap into some iron filings that are near enough (e.g. if you’re standing on a pile of them, or they’re in a pouch on your utility belt that you expect them to be in - so if that pouch was empty but you had iron filings elsewhere, tough, that wasn’t what you were thinking about so you don’t get the bonus)?

Transfer requires a drop of your blood. How recent does it have to be; does it have to be bubbling off a vein, or can it be in a glass vial or something? If the latter, how often does it need to be refreshed?

Cleanse Spirit requires a burning candle, which implies that you need two fast actions to get it ready: one to fish it out of your pack / your superhero bandoliers, and another to light it. This seems unfair.

Immolate can use a torch or an open fire, which implies that you don’t need to be holding the material component in your hand (how could you?).

Blood Channelling says you must sacrifice your living victim before you cast the spell. But how soon before? The minimum expenditure is 1 WP, and you get at least 2 WP to spend on the next spell, but if you rolled a 6 you’d get 4 WP to spend, so it’s a minimum net +1-+3 WP for a cost of one action. Assuming a fast action to grab the victim and a slow action to kill it, that gets you to an additional net +2 WP. That’s useful as a final resort - grab rat out of your pocket, stab it, cast a final overpowered spell in defiance of all odds - but it seems to me that a villain surrounded by the corpses of their recently-dead cult followers should be able to tap into their blood for quite a while before the blood runs out or an enterprising PC summons an indoor thunderstorm that washes all the blood away.

(1) Ingredients need to be near, but you have to know where they are

This encourages the superhero utility belt approach: you have a whole bunch of individual pouches with ingredients individually-portioned for the spells you know you’re going to need them for. Or, if you’re standing on a pile of corpses, you just need to check how much blood is left and what your next source is going to be, which should normally be a free action.

(2) You need to focus on the ingredients but don’t need to touch them

You can still do the standing-on-a-pile-of-corpses thing, but you can also make your grimoire really cool because as well as it providing a magical reminder of what the spell is all about, it also contains ingredients.

I think most people when hearing “grimoire” will think “big hardback book with many, many paper or parchment pages”, but I don’t think that’s justified. You open your grimoire at the right page and you cast the spell; there’s no thumbing through many pages or reading out stuff. The process of copying a spell into your grimoire takes ages, and there’s a Scriptorium building that explicitly helps you. I think it reasonable to assume that the “page” that you copy the spell into has had the spell cast into it many time. I suspect that if it started out as parchment or paper, it’s now much sturdier, because it’s now full of magic.

And the thing is, if there’s only a small number of pages in your grimoire, and each of them is pretty hefty (because they’ve had a whole bunch of magic cast at them repeatedly), it’s not a huge stretch to say “there are a few compartments in each page for ingredients”. Opening the grimoire at a specific place reveals two facing pages; as well as mystical markings that will almost certainly shimmer into mystical gold filigree when the caster does stuff, there’s a small transparent box containing an ingredient, and when the grimoire-owner casts the spell, looking at the ingredient, the mystical markings will flare up and the ingredient will get consumed in a blaze of magic. (Unless this was the stealth spell.)