Casting Requisites and Enchantments

Games Discussion Ars Magica
1

So, my question is kinda obvious but after all the reading I've done I still don't think I've stumbled upon the right answer.

I understand that you can design spells that allow for extra effects by including additional requisites the moment you cast them, without the necessity of inventing the spell with those requisites added. So you can learn The Unseen Arm as a Rego Terram spell, then cast it with Herbam requisites and move something entirely made of wood. Or you can cast the Conjuration of the Indubitable Cold with Rego requisite to avoid freezing yourself. I assume that this involves the fact that casting requisites are a modification simple enough to a spell that a magus is able to make it as he casts the spell with no extra difficulty added (other than having the proper level for the requisite, of course). But how does this work on enchantments?

Initially, I would consider that you must create the enchantment with those requisites added already. So a wand of The Unseen Arm that is supposed to move anything solid, would be ReTe (AnCoHe), but since this doesn't impact the difficulty of the spell itself, it shouldn't impact the creation of the enchantment either. However enchantments seem to me "plastic" enough in some cases to allow for the user to add those requisites himself. Spells with Concentration duration and modified effect, for example, are pretty mutable in terms of imput, so that you don't need to include them when they would be considered casting requisites for an analogous spell.

So what do you think?

2

Actually, the rules seem pretty clear to me that you must include any requisites you want the item to be able to use at the time of the enchantment. That's because it is the item that is "casting" the effect, so it needs some "knowledge" of that Art.

The user doesn't have the ability to add a casting requisite when activating the item. In fact, most users wouldn't be able to do so since they might not even have the Gift.

3

Indeed.

ArM5 p.115 Casting Requisites implies, that a magus casts a spell. While an ArM5 p.98 effect in an item "is not a spell".

Cheers

4

I agree with Arthur as well. You'd need to account for the casting requisites at the time of item creation or it wouldn't have them.

5

But investing the effect with those additional requisites wouldn't impact its level, in the same way that it doesn't when casting the spell with them, or would they?

6

Not if they are just being used as casting requisites. Then all it means is that you use the lowest relevant Art.

7

Yep. Just one of the things that make spells and devices different. Devices aren't affected by casting conditions as spells are. But spells can have a little flexibility worked into them by the caster.