An interesting bit of a bug that can be extremely useful in making very powerful spells:
If you put a shape in the Shape Group(using Zone as an example here), then put 3 modifiers in the Spell Grammar(duration as the example), then put a shape in the spell grammar after that, you will be able to put the modifier in again. However, you can still put it in the Shape Group, allowing you to get up to 6 modifiers of the
same type, allowing for some interesting stacking. (In the case of a 6 duration-boosted Zone, it lasts for I don't actually know how long, but a 5 duration-boosted one lasts 10 minutes of real time.)
Due to this being put after Shape Group, only modifiers that affect shapes can really work.
To my knowledge, the following modifiers stack:
-Bounce, Duration, Gravity, Piercing, Range, Rune Procs, Speed, Prosperity
(Solar and Lunar also stack, where applicable.)
To my knowledge, ones that
do not stack:
-Radius
All others affect spell components, not shapes, and therefore do not actually do anything when you stack them like this.
A particularly powerful(and useful) spell I have made with this is:
Phylactery:
-Zone
-Duration x6(using the method I just described)
-Self
-Chrono Anchor
This effectively sets your 'life' to when you cast it, and if you die anytime throughout the spell, will simply return you there. There's no need to put Duration on the chrono anchor, because it's applied every second of the really long time. This also makes it
incredibly difficult to counter. The mana cost is a measly 39.69(no burnout), which, for a spell this powerful, is incredibly low.
A second spell I created using this method(I have a fondness of long lasting zone spells, they seem to be quite powerful for their cost)
Gigadrill(probably a lame name but whatever):
-Projectile
-Zone
-Duration x5
-Zone
-Duration x3
-Gravity x3
-Area of Effect
-Dig
-Mining Power x3
This basically creates a 3x3 drill that goes downward wherever the projectile lands, constantly breaking downward until it hits bedrock. It costs a mere 75 mana for the initial cast, and will remain for 10 minutes after casting, which allows the drill to go down pretty far, as well as break anything placed inside for the duration of the spell. Can be quite useful, especially for clearing out a
really tall area, or demolishing a tower. This can be used for griefing, but please don't be that guy. Nobody likes that guy.
Before attempting a duration x6 or x5 anything, I recommend trying it on a singleplayer world, simply because if something goes horridly wrong with the casting, you can end it simply by shutting down the world and bringing it up again.
EDIT: Found out how long the x6 lasts; it seems to last 15 minutes.
This method still works with the newest Ars Magica 2 version(version 1.4.0.009), and for any creative minds out there, I recommend experimenting with it, see what you can do.
EDIT 2: Sextupling a modifier as listed above no longer works. :c