Clarification on the stats when Changing Creature Sizes in Ars Magica

Many spells change the size of a person or creature, or creatures have their size altered to suit the story needs of an Ars Magica saga. I’ve been asked several times about changing size in the last month (mostly because my blog post on gigantism had an error) so here is what I’ve sussed about it. Broadly speaking the spell mechanics are variable, so please see your story-guide.

  • Each +1 mag in spell design will add 3 size levels (note some spells sampled from the core books seem to use +2 levels instead, but there has been much discussion and the fair middle ground seems to be +3 per mag).
  • Each +1 mag in spell design will reduce size by 6 levels (again variable by books, some spells seem to be able to reduce by a far greater amount than increase, I think that is primarily because once a creature is smaller than size -4 they have such low wound levels than it is almost moot).
  • Each +1 Size = +2 Strength, -1 Quickness, +1 point in the wound level damage ranges (see HoH:MC p. 39).

That means changing a soldier from normal (size +0) size to size +2 adds 4 strength, subtracts 2 quickness, and alters their first “light wound” damage range to 1-7 points instead of 1-5. That might not sound like much of a change but it makes the soldier far more offensively oriented. Slower, harder to kill, and able to inflict more damage.

This is also why reducing an opponent down to -3 or smaller is very effective, it might make them quicker but they have radically reduced wound levels for penalties, which is savage in a prolonged battle.

There is also a point at which the difference between the attacker and defender becomes so extreme that the defender really shouldn’t be able to “parry” to defend.

A rationale is: A mouse can avoid the boot of a man easily due to speed, but if the man successfully steps on it, then it really should be dead, or mostly dead.

So how big does your shield grog need to be to just squish opponents? Well I’m not sure. The size increases are meant to be 10x larger per 3 size ranks, but there is not a formula that shows how tall a person is per rank (a project for a rainy day?). Size 0 human vs a size 10 dragon seems altogether a massive challenge.

a giant fighting several folk, couldn't find the owner/artist - pretty good though eh?

Substitute Finesse checks with complexity modifiers?

Discussion post – Is it reasonable to add magnitudes into Ars Magica spell designs which substitutes Finesse rolls with complexity modifiers?

By RAW no. However as a house-rule it has merit and also is sort of implied by the core rules before all the expansion rules were added. Playing Ars Magica with Core Only is very different from using all the new rules. In fact playing with all the rules would be mind boggling, so a few more choices to suit how players might want to play isn’t breaking. YSMV.

In the base rule book the Finesse skill is not given the same degree of importance to Creo and Rego magic, specifically because new guidelines were introduced in other books.

As example – A Rego specialist Magus could be designed with a moderate Finesse in core, but would be next to useless in the expanded (now very RAW cannon) Finesse rules; primarily because the target numbers for Rego crafting magic and by extension Creo magic are ridiculously high.

How high? Well a Finesse check in the mid-20s isn’t uncommon, and 30+ is needed for the really cool stuff. In a game with 1d10+skill(1-6)+stat(1-5) that’s punitive.

I previously wrote about using time as a mitigation for Finesse checks for Creo ritual spells, and I think the suggestion makes sense. Essentially it allows a high degree of preparation to mitigate the Finesse roll, as long as the spell also has a complexity modifier built in (just as Conjuring the Mystic Tower has, which was a spell written before the expanded Finesse rules). This allows a way to rationalise the rules where one ritual spell does not require a Finesse roll, but the instant Rego/Crafting spells still do.

So what about expanding that house-rule to allow additional mags to add a bonus to the Finesse check?

Suggested new Guideline:

Caster gains +3 bonus to the Finesse check for each Magnitude added for Finesse Complexity in spell design. This complexity may only be added where the description also produces a higher quality and beauty item, and must produce a more specific result for each step in magnitude.

I’m a supporter of this principal too, as I see spell complexity as a representation of increasing detail mandated in a spell (as if the spell is an architectural design or a script).

I also like the idea that magic can have many ways to do the same thing, and a spell designer could build knowing that their version of a spell is far higher than another wizards, but they get to an almost identical result.

Along with that Finesse check should be a restriction on the purpose of the spell. A Creo spell to create a sword could have a lot of variety in the result. A ritual using this suggestion to create an ornate and wonderfully crafted sword should note what the additional complexity is for.

This ensure that the complexity added for component parts, or high detail is different from the “complexity for Finesse replacement”.

Quoting from and E.g. from the Atlas Forums by Virgileso:

Echo of Durendal

CrTe 40, R: Touch D: Momentary T: Individual

This spell creates an excellent quality steel longsword, granting the wielder a +4 Attack & Defense in combat due to its uncanny craftsmanship.

(Base 5, +1 Touch, +6 complexity)

Designer’s Notes: Rather than requiring a Finesse check against an EF 30 for such a sword, I am instead obliviating the roll altogether and setting the spell’s crafting total to a flat 12+(3*complexity) against an EF as per the Rego Craft Magic guidelines set forth in Covenants.

I don’t think it’s game breaking. My interpretation of the spell above would be that it will create an identical weapon each time it is cast because the design adds 6 magnitudes for the Finesse bonus.

It is a different style of solution to adding time (above), and while it’s plausible that these options might be used in combination a table of players would probably need to pre-select if either option was allowed and carry that forward in their games.

Happy games folks.