Mechanics: Sorcery

You'll need this.

Today I'm only going to be covering one system, because there is no sister system for Sorcery. Well, it is a magic system that uses advantages as spells, so technically, there are a lot of compatible systems. No matter, what I am discussing today is *The* Powers-As-Magic system. Sorcery is probably one of the most mechanically simple of all the main magical systems with mechanically consistent rules that stick to fundamental core concepts of GURPS. Let's look at it closer then.

Sorcerous Empowerment

Sorcerous Empowerment (also called Sorcery in the supplement; they just wanted to distinguish the advantage from the system) is basically the Magery of the Sorcery system. This advantage enables two key functionalities of Sorcery. Number 

1. It enables improvisation of unknown spells using the modular abilities rules from the basic set.
2. It enables buying spells using rules for alternate abilities from the basic set.

This advantage itself is not a talent like Magery usually is. Buying extra levels simply unlocks higher tiers of spells.

Sorcery Talent

As mentioned above, the "talent" component is split off of Sorcerous Empowerment. Like most power talents, additional levels of Sorcery Talent add to skill rolls when any Sorcery advantage or skill is used. One special note here is that there is one special case where one may use Sorcerous Empowerment as a talent instead: when casting against countermagic, a character can add the higher of the level of sorcerous empowerment or talent instead.

Learned Spells

Sorcery takes advantage of the alternate ability mechanic from the Basic Set to make spells cheaper. Spells are advantages with the -15% Sorcery power modifier [Which is a combination of -5% for Costs 1 Fatigue and -10% for Mana Sensitive; this is important because sometimes we use the -10% Mana Sensitive modifier instead if a spell already costs FP to cast.]

Since Sorcery uses the alternative ability mechanic, the full cost of learned spells must be less than the entire point investment in Sorcerous Empowerment. That is, if someone spent 40 character points for a given number of levels of Sorcery, they can take any spell that cost less than 40 points, and divide the cost by 5 as you would normally do with an alternative ability.

A key weakness of Sorcery is that since spells are built off of the alternate ability mechanic, maintaining multiple spells is next to impossible. I say next to impossible because there is one expensive solution: if you pay the full price of a spell instead of taking the alternate ability discount, you may cast a spell and maintain it separately from the rest of Sorcery.

Improvised Spells

Sorcery has two types of improvised spells, Cantrips which can be cast as easily as any other spell, and "Hardcore Improvised" spells. That is literally what they are called.

A cantrip is a spell that costs less character points than a character has Sorcerous Empowerment levels. Eg, if someone has Sorcery 7, cantrips are any spell that costs 7 points or less without an alternate ability discount. With moderate investment, this means Sorcerer characters might be able to use weak attacks or small utility spells for free; with a tremendous investment, they can potentially cast anything.

The more difficult and complex component of improvisation is "Hardcore Improvisation." This lets a character improvise any spell that costs up to the entire point investment in sorcery; someone who invested 80 points in sorcery could potentially cast an 80 point spell without spending any character points on it. This comes with a very steep negative modifier that depends on the ratio of points of the improvised spell to the points invested in sorcery, along with a larger energy investment requirement. A character however that carefully invests in levels of Sorcerous Empowerment along with Sorcery Talent might be able to improvise some very useful spells at little difficulty however. GM's should consider capping Sorcery Talent, unless they are fine with a player being able to cast any spell with no penalty without learning it. It would be kind of expensive, but with a roughly 210 point character investment, a character could be massively destructive without having to learn a single spell, unless the Sorcery Talent level is capped. 

Improvisation is a very powerful tool of the Sorcery system, but spinning up new spells can take a lot of time. If you feel you and your players are not up to the task of calculating spells on the fly, and you are worried that looking up formulas and modifiers can bring the game to a halt, you could rule that the only spells that can be improvised are those that are already written down somewhere, or maybe even give them a small discount on Sorcerous Empowerment for the limitation of "Not able to use hard core improvisation" Which might be worth -5% or -10% in my opinion.

Creating Spells

You will almost certainly need
this book if you want to create
your own spells.

Spells are built the same way as any advantage, but there are a few recommended guidelines given in the Sorcery book for better homogenization; that is, simplified rules, because if every spell implements a few particular rules like "always costs 1fp and always takes 1 second" it requires less lookup of boring minutiae to use a character. These are not mandates though, and even in the included example "grimoire" of a decent number of spells the rules are broken a few times when it would be cost prohibitive. Often, when the rules are broken, an "improved version" of the spell is included with all the prescribed recommendations followed so that a player can buy the cheaper version at a discount, and then pay the difference when they earn more character points.

Creating spells is the most complicated part of the system, and I prefer to handle it off-line [not in a session] if possible. I am a number crunchaholic though, so I am often tempted to stat out spells immediately if given the chance. This can vary from group to group though. Some might not mind taking a 1 to 2 minute break [this is what it takes to come up with spells after doing it a few dozen times, probably more like 5 to 10 minutes at first.] Others will find it a very unnerving interruption. Hash it out with your fellow players and GM.

Existing Spells

Here's the fun thing. Powers are a pretty universal system, so there already exists a huge library of statted out spells, they just aren't called that. The only problem is that -15% is a kind of rare power modifier and the most common modifier is -10%. This means that most powers you find will be just a tiny bit cheaper when converted to the sorcery power modifier. However, make sure to look at FP cost on any appropriated powers. If you want to make it a regulation spell, you might need to do some more tinkering according to the rules mentioned under creating spells, like making sure it costs exactly 1 FP and takes exactly one second, which can end up making the spell a lot more expensive than the original ability.

Other Useful Material

• Basic Set - Characters is often all that is needed for creating new advantages. It already has the majority of advantages and modifiers to customize spells. If you allow players to use hardcore improvisation, this and Powers are practically required.
• Powers has a few extra key advantages and modifiers that can help with a few important edge cases when creating new spells.
• The Power-Ups series has more good advice on spinning up advantages.
• Power-Ups: 1 Imbuements is especially useful as Sorcery weapon buffs are predicated on this system.
• Power-Ups: 4 & 8 limitations and enhancements might have more customization options, but I have not read them and personally can't vouch for them. I heard they are more like compendiums and if you already have a lot of the other important power books, they might not be immediately useful.
• Many other books contain advantages already turned into power abilities and can be easily retrofitted to Sorcery. For example, Divine Favor, another very interesting powers based system, has a lot of clerical "prayers" that can almost immediately be converted to sorcery by taking off the -10% divine modifier and changing it for the -15% Sorcery modifier.

Final Notes and Closing

I would still contend, of all the popular magic systems for GURPS, Sorcery is the easiest in play. Even with the concept of improvisation. Without Improvisation, it is undoubtedly the easiest. I have not used the system, but I have created many spells for it, and if anyone is familiar with creating abilities for another powers based system, they will already be 3/4 of the way there to mastering Sorcery. No two different spells being cast simultaneously sounds like a real drag for players that like buffing allies with several different abilities. Making interesting single digit character point cantrips is a lot harder than you'd think; I tried. I think of the tens of sorcery powers I made, less than four came in under 5 points. That being said, a system with a relatively easy to use, and hopefully balanced and self-consistent set of modifiers means I'm more confident making new abilities that feel balanced in Sorcery than many of the other popular systems.