A thought on affecting spells with requisites, a meta-magic question for Ars Magica

An aside – How do requisites affect which spells can be affected by magic?

A question raised during the forum discussion asked if a Muto Vim effect could change a spell enough to make it no longer effected by a Perdo Vim form specific effect. e.g. A Sun duration Rego Terram effect is altered to a Rego Aquam effect at cast time – can a Perdo Vim/Terram spell affect it if it has “changed” the form it uses? Further could the same Perdo Vim spell affect only Terram spells, or can it also affect spells with a Terram Requisite?

I tend toward thinking a spell with a Tech and two Forms can be affected by either Form specific dispel effect. The unraveling affects part of the spells structure and it doesn’t really matter which form it unravels to make the spell loose it’s cohesion. This makes requisites a slight disadvantage, and implies that some part of the original spell is still there to be unraveled.

But I hold the same concept to other ways of affecting spells it also introduces an advantage to Mu effects affecting the Forms too. i.e. a Muto Vim Terram spell to alter Range up by 1 mag can be applied to any spell using Terram, either as the base form or a requisite. I don’t see adding breadth of application into Vim spells as unbalancing.



Complexity in Muto based Materials Manipulation

This post is more meta-magic system thoughts for ars magica –  on the complexity in Muto based materials creation and manipulation, raised from a forum discussion…

Switching one form to another should include a degree of flexibility in the final shape, as this is the declared purpose of the spell. As long as the spell is creating a specific object or thing. Surrounding air to a natural plant is fine and declaring the type and shape of the plant is reasonable in the Formulaic formula at base.

Then modifying for complexity in shape seems appropriate, as:

  • I see the complexity as quasi- geometric shapes (+0 mags) like lines, cubes, boxes, or walls. Exploiting a feature of the new material should be free too – like using a plant to create a natural shelter.
  • The allowing sub-shapes in the main shape (1) like windows, basic stairs, spikes.
  • Then almost any other ordinary detail (2).
  • Then finally very ornate details as (3) like artwork.

Having the additional mags should allow forgiveness in the Finesse check but not remove a basic “fit for purpose” check. A serviceable but ugly level for a simple item is vs 6 (a sword), and a more complex item is vs 9 (a suit of armor). Less than this and the finesse check might still be needed (vs 3) , but is really at the “don’t botch” level (a cube of stone).

So a basic sword is +1, and a full suit of armour might be +2. Then add mags for moderate flexibility in choice of form when casting. Making a spell which can pick when cast from a dagger, knife, or sword should cost something, whereas two different styles of swords which are serviceable seems plausible as a spell without too much added complexity. Sword vs axe should definetly need complexity modifiers, if not be allowed at all.

Ref: Atlas Games – Ars Magica forums.

And perhaps interrelated is the Creo vs Muto discussion here, or replacing Finesse with magnitudes of difficulty

Fire to bubbles