How would you design a magic system for a Harry Potter style of play?

[DM-Rocco]

I've actually been kicking this very question around for the past couple weeks, and having just finished the 7th book (very good, BTW), I'm left with the conclusion that a Harry Potter magic system would almost have to be far more free-form then most of the magic systems I have experience with (with the possible exception of True Sorcery).

The 7th book is loaded with new spells never shown in the previous books, and while there seems to be very little in the way of new spells created, the list of existing spells is simply immense. I suppose what could be done is create a list of some of the more common spells (and their effects), but leave the door open for players to "create" new spells (in a far more free-form manner then most systems), but instead of them being created, they're simply learned from some dusty tome.

As for the system beyond the spells, limiting it in any way to some list of "spells known" simply feels off, unless the list is extremely large. I could see some sort of skill system, where a certain number of points have to be placed into a spell before it sticks with you (or perhaps you need X number of points, and before that you have a substantial failure chance, or a penalty to Spellcraft).

IMO, the biggest hurdle for doing something like this is that the magic system is going to be a central focus of the game: there really aren't anything akin to fighters, rogues, clerics, etc, so the spell system *is* the game. For the game to be more then a passing interest, the magic system would have to be quite versatile.

I finally finished the book last night at 3:00am, I finally got away from the wife and kid long enough to finish it. Really good, but I wanted more detail in the final chapters, but that is another thread.

They explain a bit about the wands towards the end, so after I think about it a bit more,I might have some more ideas.
Where can I review the ascenion rules? Is that a hard copy book or a pdf?

 

[DM-Rocco]

You know, I'm actually writing something at this very moment (in another window) that would work very well for this. It's archetype-based magic that requires a character to expend a point of Mana (for balance purposes) and make a 'skill' roll to cast a spell (said roll consisting of chucking a number of dice equal to the rating of a given archetype). In d20, I would swap out the default archetypes for skills specific to classes taught at Hogwarts.

By all means, feel free to post your ideas here in this regards.

 

[Hjorimir]

There seems to be a spell to fix anything in the Potterverse. My gut reaction is True Sorcery, which allows for the creation of all kinds of effects. You might be able to get a lot out of the way with some kind of prestidigitation on steroids spell where characters could do pretty much any minor thing based on a skill check.

 

[smootrk]

How many spell-based classes are there at Hogwarts? Charms, Transfiguration, Dark Arts/Defense against the Dark Arts ... if each of those were a skill, it'd be a lot more manageable, and you could set the various "spells" with their own DCs, some of them super-high, some of them low (like lumos).

This is the way I would group things as well. I would make wands a standard focus item, and without which one would have a substantial penalty to DC of casting (but theoretically possible). Some endeavors such as Potions study or (most) Divinations would not need this wand focus; but most evocation or directed magics would need to use a wand.

In addition to standardized spell effects, I would allow for improvised spell casting as well (at a substantial DC), but this would allow for a wide range of spell effects possible. Certain spells would be physically or mentally draining (as such dropping CON or INT, thus making continuous castings of powerful spells more difficult as one continues).

For a really complete listing of spells, effects, and related information check here (came across this a couple of days ago):
http://www.hp-lexicon.org/index-2.html
specifically look to the Encyclopedia of Magic and the Magic and Magical Theory links. The other links provide a wealth of information for other HPish aspects such as Quidditch rules and some rough maps.

 

[GreatLemur]

Yeah, if you're going to start from d20, I'd definitely lean towards skill-based casting, as a lot of folks have suggested. I think using multiple skills is a particularly good idea (especially since it diversifies character builds, instead of making Spell Focus: Spellcraft and Magical Aptitude into absolute must-take feats). We could have a skill for each broad category of spellcasting; a quick look at Wikipedia suggests Transfiguration, Charms, Defence Against the Dark Arts, Divination, and Arithmancy, and I think I would also include a Potions skill, treating that as a type of spellcasting instead of using the Craft rules. Apparition probably warrents its own skill, too: Sure, it only does one thing, but it's a tremendously useful thing. Casting would require a check, and success would be almost certain as long as you aren't casting your most difficult stuff, or under poor conditions (which would include, of course, things like casting without a wand, with someone else's wand, without speaking aloud, while distracted, etc.). And there would absolutely need to be a mishap chart for badly-failed spells.

I don't think I'd put a hard, level-based limit on learning new spells. Just as with D&D Wizards, I think it'd make the most sense to have learning a new spell require time and a Spellcraft check (that way, you've got a skill that's required for learning, but not for casting, so you can have your studious Herimone Granger-types who are quick learners, but no great prodigies when it comes to actually wielding magic). This would go for learning new potions, too. There might even be different levels of Apparition that could be learned, although that might be reaching a bit.

Flying probably deserves its own skill, as well, but wouldn't exactly be part of the spellcasting system.

As Roudi pointed out, the main balancing factors of magic would be story-based: The prohibitions against using magic in certain places and in certain ways, and also things like time constraints and access to knowledge and resources.

 

[jdrakeh]

By all means, feel free to post your ideas here in this regards.

I'll post the PDF file (Bastard Sword!) for free download in my .sig when it's finished. Somebody asked me what a serious Risus would look like a while back. That's more or less what I'm working on, albeit with special dice (because I needed to find a way to make this block of 50 blank, six-sided, dice that I ordered a worthwhile purchase).

 

[FrouzenIland]

All right, I also post on WOTC forums. Some people definetly should be entitled to share some of SWSE profit... really!

What about using the Skill-Based Spellcasting system created by Patrick O'Duffy?
You can check it in The Year's Best d20.

 

[DM-Rocco]

All right, I also post on WOTC forums. Some people definetly should be entitled to share some of SWSE profit... really!

What about using the Skill-Based Spellcasting system created by Patrick O'Duffy?
You can check it in The Year's Best d20.

Not that I'm lazy, er, okay, I am lazy, but can you just post a link to that.

I was messing around a while back with a skill based magic system, sort of based on the Epic spell casting rules. I took out the broken things, like being able to reduce spell casting cost with other casters and take damage from the spell to reduce the DC (the two main ways it can be broken). It still needs work, but it is more of a free form spell casting system I was going for, instead of memorizing spells. Something more Harry Potterish where you can just cast the same spell over and over once you learn it, but you had to make a concentration, Spell Craft and Arcane knowledge check with every casting and you need a to hit roll for every spell. Failure by five or more still works, but with unexpected results. Anything less and it back fires. Can't use magic items to increase your skills for this purpose, otherwise it just gets nuts and broken. It gets a bit heavy on the die rolling, (four d20s and then damage dice with every spell) but I wanted something with range, but balanced. Like I said, it still needs work.

However, I would like to see what others have come up with.

 

[DM-Rocco]

The trouble with Harry Potter magic is that the subjects taught in school don't really map to mechanical effects very well, and we're not given any kind of underpinnings or explanation of what's going on. That makes it difficult to pick up any kind of mechanical basis from which to extrapolate a system.

That is one of the things that is both good and bad about a Harry Potter style magic. It is like playing an illusionist. The same spell, a jinx spell for example, can be used to different effects each time. Hard to track and know what it is capable of, but you can do a lot with it.

For example, why are some things potions? Can you cast a charm that has the effect of drinking Veritaserum? How about Polyjuice Potion? Is there a reason for this difference? What differentiates charms from transfiguration?

I think you have to eventually specialize in one or more areas and then ar not as good in others. Like animagi can cast better transfigurations than a seer. Notice Hermione could cast just about any spell, but really sucked at prophecy. Hmm, I guess in the end even she needed a potion. Who knows.

That being said, if I was going to set up a Harry Potter game, I'd probably use the skill tricks mechanics from Complete Scoundrel, or something similar, combined with a Warlock-like Wizard class. None of the characters in the books ever get tired from casting spells, nor do they run out of any kind of magical energy. Different spells would have different levels of power, and you have to be a certain level to learn them. They would cost skill points, or some of the free 'spells known' points you get as part of being a Wizard. Spells would require skill checks, probably with some sort of backlash mechanic if you critically fail. You would be limited by the number of actions you have, rather than the number of spell slots per day; more powerful effects would require longer casting times, for example.

I'm not sure if I'd have different skills for different types of magic. Probably - it seems like there are different skills, after all, and not everyone's equally good with everything. The trick would be figuring out how to split it up. My tendency would be to use D&D schools, or something similar - differentiate by effect, rather than flavor. Defense Against the Dark Arts would mostly be Abjuration, with a few Conjuration effects (the Patronus, for example). Charms seems to be all over the place, but primarily Evocation and Enchantment. Divination seems to be not particularly useful. Transfiguration would get its own skill, I think.

There are thorns to this approach, but you could model the basic setting of HP fairly well with it, I think.

I really don't know much about the warlock, I think I might play one in NWN2 just to get a better feel for them, but you might be right about that. It does seem to fit better. I think something between a warlock and a psionicist.

 

[Gothmog]

Actually, its already around and has been for a long time- Ars Magica. Magic is split into forms and techniques. Forms include things like Animal, Aquam (water), Auram (air), Corpus (body), Herbam (plant), Ignem (fire), Imaginem (image or illusion), Mentem (mind), Terram (earth), and Vim (magical power). Techniques are how you act upon the form- the techniques are: Creo (creation), Intelligo (perceive or understanding), Muto (change), Perdo (destroy), and Rego (control).

Each form and technique is treated as a separate skill, and when you can to cast a spell or create a magical effect, you combine a form and a technique. For example, to cast a charm to make someone more predisposed to you, you'd use Rego Mentem. To snuff out a fire, Perdo Ignem, and so on. Wizards know some spells by heart, called formulaic spells. In addition, they can also improvise spells on the spot using their magical skills. Spellcasters can cast unlimied spells per day, but they run the risk of becoming fatigued, or suffer a spell botch, which can have serious consequences. Its the best approach I've ever seen to magic in a game.