Geode Casting

[Centaur]

First, Somebackground.

In the world that I am running, I have magic flowing directly from the ground itself. Magic is strong when in contect with solid bedrock. In particular magic, or "mana" flowes the strongest from the mouths of volcanoes and open active fishures.

Durring eruptions, sometimes lava cools into the form of geodes. They come in many forms, from Agate, Amathyst to quarts and other forms. In this world, when they form, they trap some of that raw, untapped mana within their core.

For this reason, geodes are highly prized as a source of pure mana for the creation of magical items. The mana in them can be used to offset the XP cost of building magical items. When Geodes are found, they have a rating of from 0 (flawed) on up. Large well formed geodes could have ratings in the 100's. Each rating point values the geode at 25gp and is offsets the XP cost of items they are used in on a 1:1 basis.

There is a new feat in the game called Rune Carving that is needed to access this power. An enchanter combines "Scribe Scroll" with "Rune Carving" to create a geode that can be activeated like a scroll. it is of course harder to carry around a bunch of rocks than peices of paper, but cheaper in the XP department.

Likewise, the combination of "Rune Carving" with "Brew Potion" allows the making of a geode that can server the same purpose as a potion, without the need to consume. The list of cominations goes on and on and ....

The Proposal
I would like to setup something in the game that would allow spell casters to use these Geodes to augment their spellcasting. I have a few ideas on how to proceed with this, but I thought I would get some input from the comunity.

One option was to allow the Mana from the geode to augment the effective level the spell is cast at either on a 1:1 or 1:2 basis or even at the square root of the rating (ie a rating 9 stone would add +3 to the effective level).

Another option was to allow the power in the Geodes to compensate for the level modifications of metamagical feats. Not sure one the ratio again.

Another option, would also to allow the power in a geode to act as a one shot Pearl of Power. In this case, I think I would do at least the square root of the rating to see what the highest level spell could be restored is.

What do you think about any of these. How would you run it and does anyone have any other possibilities.

 

[Mordane76]

I think rarity will set the ratios.

If the geodes are rare, even the basic ones, then you can safely apply a 1:1 ratio.


However, you might not want to, because if power ratings can go into the hundreds, then a lucky player will search for (and find) a 400 rating geode and use it to maximize and quicken everything until he burns it out (which obviously will take a long time).


What's the range, and where are you placing the average power rating of these geodes?

 

[Centaur]

Most geodes found are going to have a value of between 0-20. I haven't figured out how to generate them yet as treasure (I am in the middle of revamping the system from the DMG so that it provides a little more variety.

as a general rule, most geodes generated randomly will have a rating of either 1D6, 2D6 or 3D6 and will weight, on average 1 lb. per rating point. Some very pottent geodes may weight as little as 1/4 lb. per point while others could be as high as 2-5 lbs. per point.

For Geodes of higher values to be found, they will be placed as a specific treasure. Theoreticaly, there is no upper limit. Many of the larger cities use a huge geode (value in the 1000's) for the making of a "Center Stone" for the city on which are placed several protection enchantments to prevent certain spells from being used within or against the wall of the city (no fly, no invisibility, etc...).

I was also thinking that in order to use the stone, you must crack it or some other damaging thing msut be done to access the mana. This means that While a character could find a 400 point stone, he still could only use it for one spell or one magic item. it is not a tapable resource.

The one exception to this is some geodes have a qualifier on their rating of R (ex. 25R). This means that the Geode is so perfectly formed, that the mana field within is a regenerating commodity. I havn't decided how long it takes to regenerate or what this would mean fro making of magical items from them.