Harry Potter and the skill-based magic system

Someone posted another thread about using a skill-based magic system and it got me thinking.

I was rereading the Harry Potter series a few months back and it occurred to me that a Harry Potter RPG would need to use a skill-based magic system. Everybody knows the really basic spells and can cast them as needed. The intermediate-level spells clearly have higher DCs, and some advanced spells can't be completed by any but the most advanced wizards.

Let me toss some ideas:

To cast on this system, you need to be born with the talent for it.

Any spell that can be cast on the fly requires an arcane focus-a magic wand. each wand is more or less uniquily suited to its owner, and thus difficult to replace. Spells cast with another's wand are apt to go awry.

First-level spellcasters should be able to cast the most basic spells, alohamora, wingardium leviosa, et cetera, wih a decent roll. More advanced magic, say the Patronus Charm, are tough to learn and tough to cast. The most advanced spells are available to only a few wizards and witches. This is just like the standard system, I suppose.

Some spells must be cast into potions or other items before use, e.g. veritaserum, polyjuice potion, portkeys.

Maybe you one could use Knowledge (Arcana) for what spells a caster knows and Spellcraft for what spells they can cast. Hermione Granger has a lot of general knowledge about witchcraft, though, that Harry doesn't, and clearly he can cast spells that are way beyond her ken, so that won't work.

Some magic is forbidden by law (flying carpets), some by morals, and some by both (Imperio).

Some spells are just poorly guarded intellectual property, like the Dark Mark.

Any ideas anybody?

Hum... allowing all spells to be cast based off of only two skills (Knowledge [Arcana] and Spellcraft) seems a little too easy to me... most characters could max ranks in magic skills and have plenty left over.
I've thought about this myself (coincidentally, I was also thinking about it with the idea of Harry Potter) and IMO there should be a separate skill for each type or school of magic (well, Harry Potter doesn't have 'schools' of magic, but you could make some up based on the kinds of classes they take - one for Charms, one for Transfigurations, etc). Spellcasting classes would get lots of skill points, and probably some class features relating to spellcasting, but not much else (also, a skill list that's very limited, except with regards to magic skills). You could also take a tip from Star Wars d20 and make several similar spellcasting classes: for instance, one for the smart and studious wizard like Hermione (lots of skill points, lots of spells known) and one for the less well-studied but more powerful wizards like Harry (fewer skill points, but the ability to get very good at a few spells - also possibly some mechanism similar to a Wilder's "Wild Surge").
That's just my idea on it though. Do with it what you will.

Okay, that makes sense. Clearly, you'd need different skills for the different "schools" of magic, maybe with a synergy bonus here and there listed in the spell description.

There is clearly room for a whole snotload of prestige classes, too, what with aurors and PR people and Quittich champs. All of the main characters (except Neville, so far) seem to be good at something other than spellcasting, too. Maybe gestalt progression would work. The Weasley twins look to have rogue levels. Malfoy might be a noble. Flitwick is a gnome paragon (I do really like Warwick Davis, BTW, but film or movie, Flitwick just so liiitle.

At a guess:

A skill for each 'school' of magic, including stuff like making potions and the like.

The skill roll is what determines success or failure.

The degree of the skill roll determines caster level (kinda like use magic device).

Taking 10 on spells is allowed in non-stressful situations.

There is a feat that allows taking 10 on a particular area of magic in stressful situations.

Thus, when you're limited in feats, you must choose between the ability to take 10 on the spell, or the ability to get skill focus on that school and therefore potentially succeed more often, or create a more powerful effect.

I'd suggest we also say that the ability to use magic at all is a feat's worth, achievable only at 1st level. And no - that doesn't mean using magic only needs a single feat. You still need skill ranks, a high appropriate stat (I'd suggest wisdom or charisma - intelligence already factors in when it comes to skill points) and supporting feats.

Spell DCs are set such that at a particular level, only those with very high attributes (or focus in the school) will be able to achieve them when taking 10.

Hence, when everyone's level 1, ron (with his relatively low relevant stat) has a maximum of 14 if he takes 10.

Hermione has a maximum of (say) 18 taking 10.

Ron must roll, hermione executes flawlessly.

Aim the roll such that hermione will succeed at 0 level spells (and could potentially succeed at more difficult spells). Say we make it a DC of 15 + spell difficulty.

We could even make the spell difficulty variable (alohamora for instance may be a trivial spell (difficulty 0) if the thing is merely closed, but almost impossible (difficulty 20) if it's a full-blown safe)

Presumably there are penalties for a sufficiently large failure. Say if you roll a 1 and fail, or if you fail the spell by more than a certain amount.

Finally - having non-magical abilities can be represented by the fact that you no longer need to take wizard class levels to be a wizard.

So for instance crabbe and goyle are fighters with the appropriate magic feat and skill ranks. Which explains why they're not the greatest wizards.

Hermione probably has the 'lots of skill points and nothing else' class.

Ron... dunno.

Gestalt progression might not be needed, since the characters could continue to advance their magical abilities (via skill points) no matter what class they were taking levels in.
Saevi... um, that guy above me... had a good idea with the feats. There could also be a feat which made one or two schools of magic always class skills for you ("Diligent Practitioner" or something perhaps), which would allow the multiclassing to be even more simple.

I'm currently in tthe middle of a rewrite of the magic sysytem myself. I'ts no where near complete (I just had the insipiration for it two days ago). It turns each school of magic into a skill. In order to cast a spell of a specific level, say Fireball, the character would have to have his Arcane Evocation skill at 8 ranks and have their Spellcraft skill at 8 ranks as well. In the campaign, this system would provide 'wizards' with an extra 24 skill points at first level and an additional 6 skill points at each level. The campaign is drenched in arcane magics and therefore everyone in the world has the ability to tap into the power of arcane magics. All other classes, aside from divine spellcasters, receive an additional 12 skill points at first level and 3 extra skill points each time they level up.

I'm considering though, how to approach divine magic for such a campaign. Maybe prayer points or something, I don't know.

EDIT: What I failed to mention earlier is that classes that do not have arcane spellcasting allready built in to them treat the school of magic skills as cross-class.

I'm not sure I'd agree Harry Potter magic would be entirely skill based. Look at Hermione vs. Harry. Harry is definitely the less skillfull of the two, but also has more innate power. Now, it could be that Harry has a skill focus or two, but that should show up as being better in his classes then Hermione.

Comparing them, it seems she has access to more spells (through study), and he is a more powerful caster, and he has access to a few spells she hasn't been taught, like the Patronus charm.

I think to model the books as close as possible (which doesn't mean it's a good game mechanic), each spell is a separate skill, based off a seventh spellcasting stat. Hagrid probably has an 11-12 in that stat (able to to basics, not very powerful), Hermione has a high score, and Harry has an 18.

This way - Hermione has a higher Int, so has more skill points to spend of more and higher skills. Harry doesn't have as many skills or as many ranks, but has a higher stat to base them off of so his gets the more impressive rolls, and can also cast higher level spells (using the 10+spell level minimum) like the Patronus charm.

Cheers,
=Blue

Just to chime in, I had posted a very similiar thread in the d20 modern boards about doing a Harry Potter game and some of the mechanincs that I was working on in the game. I actually posted requesting some help, but to no avail. So if anyone is interested in looking over there I actually posted a spell, that has been formatted for the skill based spell mechanic.

Blue I am actually intrigued about the 7th stat idea, but couldn't you also just model Harry off a multi-classed fast / dedicated character with a spell focus feat (and probably Iron WIll). This way he has some skill points in magic, some cool feats from fast and dedicated, and since much of the magic in HP is point and shoot as well as skill checks, he would be optimal for this. On the other hand I like the idea of the seventh stat because it doesn't add to anything else except magic skills.

Anyways heres the link to my thread

http://www.enworld.org/forums/showthread.php?t=106695

Another option would be to hybridize a couple of the options posted above. In an ideal world, each spell would be a seperate skill, but d20 really isn't well designed for that.

How about one skill for each school (for the moment sticking with the D&D definitions of the schools). All the common spells fall under the general skill (i.e., anyone with 8 ranks in Evocation can cast Fireball).

Rarer spells/abilities would be a combination of skills/feats:

Ex1:
Patronus Charm
PreReq: Must have 5 ranks in Abjuration
Cost: 2 skill points
Benifits: Add Patronus Charm to your spell list

Ex2:
Animagus [Transmutation Feat]
Prereq: Must have 10 ranks in Transmutation
Benefit: Choose an animal form you can assume via Polymorph. You gain the Change Shape SU ability to assume that form at will.

Another option would be thus:

the spellcasting classes could give bonuses to different aspects of witchcraft and wizardry.

Knowledge Wizard (the Hermione class): gives extra spells known, bonuses to Know(arcana), and general bonuses to all magic skills

Talent Wizard (the Harry class): gives major bonuses to spellcasting power, but no new spells

just an idea