Greetings fellow Mages!
1.) Been a while but here I go : Spell design : I think MuHe would do it. Spell manipulates/creates wood to form a secure shelter, prob sun duration. If you want heat, water & food I suppose you'd add ignem, aquam & Animal & maybe another magnitude to have prepared food?
2.) I am entirely confused over requisites. I simply can,t judge when a req is necessary or when it adds magnitudes? Please Advise!
Thanks much
BBB
I believe it'd be more likely ReHe as being assembled in the form of a shelter is a natural enough thing for wood to be doing. It is similar to Craft Magic in that you are replicating the work of a craftsman via magic. Now, if it were being changed to brick, that'd be MuHe.
You won't be able to add truly nourishing food or water without making this a Creo ritual; food and water created magically disappear and take their sustenance value with them when you go, so while you can summon up a nice meal and feel very full upon eating it, the next morning when the sun rises and it vanishes, you'll suddenly be as hungry and thirsty as if you'd never eaten or drunk. If you really need the rations, I'd work this part as a separate CrHe(Aq) ritual (swapping or adding An with the He as your diet desires).
Heating is much easier and is an Ignem matter, as you indicate. I suppose since it is CrIg, you might need to make the final spell Re(Cr)He(Ig) but I suppose you could probably argue that you are just trapping heat inside with magically perfect insulation and that'd leave it as just ReHe(Ig).
A requisite is necessary any time you are dipping into another Form or Technique than you already have accounted for in your spell. Since Rego Herbam is manipulating wood, there's nothing in there about heat, so you need to bring in Ignem to cover that. If you wanted, say, a fresh breeze blowing through all the time, you'd add an Aurum req. If your spell creates the wood instead of just assembles material found in situ, you add a Creo requisite.
A good rule of thumb for adding magnitudes is to ask if there is a separate effect going on. To add heating to a spell that assembles a shelter from wood would add at least one magnitude because it means the spell is doing something else completely. Typically, if the added effect is under 6th Magnitude (level 30), you add only one magnitude but that can vary; common sense needs to apply if it seems like the final result just isn't potent enough to cover what you're trying to do.
If we say the base is 5 (craft an item from unprepared timber), add +2 magnitudes for Sun, another +1 for size to make something as large as a hut (and that might need to be more if 10 paces across isn't big enough - I can't recall the details of the Tiny Hut clearly enough right now), and another +1 for the heating effect gives us a final level of 25, which seems reasonable to me.
Using Conjuring the Mystic Tower as a base, it might look something like this:
Adjust the numbers if you want something larger or more comfortable.
I think you'll need to bump the base up there a couple of notches. A hut would definitely be a "unnatural shape, such as a wall or bridge" and I would say requires treated material (cut timber, etc.). That'd be a level 25 in the end, which works since CrFo and ReFo tend to end up at the same level.
My book says processed plant products, like a finished plank of wood, are base 2.
This is true - I've done that before. They mention the bump at the top but then include it in the list of guidelines, so I tend to double apply it.
That brings it back down to 20, but I also forgot to correct for the potentially desired Ignem effect. If that's added to the Creo version (where, honestly, it makes more sense in terms of being CrIg instead of ReIg), that'd be back up to 25.