Well its been a little while but work progresses on the Harry Potter d20 game. I have all the work done on the base d20 modern classes (not that they required a lot of work) and most importantly I have codified the rules for the skill based Spellcasting system. So far I have about 65 spells written out (some better than others, but -meh). Here is the rules, and I would like to especially thank JimAde for spellcasting modifiers, WoT for the Concentration rules, Blue Rose for the Winded fatigue condition, and of JKR for the world of HP.
SpellCasting
Spellcasting within the world of Harry Potter is what defines each character as a Witch or Wizard and is central to many activities that take place within the Roleplaying Game. Unlike many other RPG’s, the characters of Harry Potter do not cast a spell and then suddenly forget it, neither do they have a set number of spells that they can learn or even cast in a single day. The Wizards of the Harry Potter d20 game are able to learn as many spells as they are able to acquire and understand, and they may cast those spells as often as they like with some exceptions.
Each spell within the Harry Potter game requires one or more spellchecks in order to be successfully cast and each one of the spellchecks require the use of one or more magical skills. These magical skills include the following;
Counter-Jinx: Spells involving the protection against and destruction of other magic.
Charms: Causing people and object to behave in ways other than that which is normal.
Conjuration: Calling forth energy, objects and even animals from nothing.
Divination: Spells dealing with understanding and information gathering.
Glamour: Spells which fall into the realm of imagination and the senses.
Hexes & Curses: Hurtful spells which cause pain and ruin.
Healing: Complicated spells which mend the body and even the mind.
Potions: Powerful concoctions which embody many wondrous effects in a material form.
Summoning: Spells which control movement and motion.
Transfiguration: Enchantments which change one thing to another, to enhance, or to alter them.
Warding: Varied and complicated spells that encapsulate an area to protect, confine or harm.
Weather Witching: Primal spells that affect the wind and weather, requiring great skill.
These magical skills are only available to Wizarding characters and are used to cast the many spells of the Harry Potter game. Each use of the skill takes a particular amount of time given in the skill’s description or in the individual spell. In order to successfully cast a spell the player must make a Magical Skill check, Roll a 1d20 and add your skill modifier for that skill. Your skill modifier incorporates your rank with that skill, your ability modifier for that skill, and any other miscellaneous modifiers that may apply (feats, wand, etc.). The higher the result the better it is. A natural 20 on a skill check is a Critical Success, though it may not be an successful skill check, which re-rolls the check and adds another +10 to it. A natural 1 is a Critical Failure and usually the spell backfires in some way.
Magical Skill Check: 1d20 + skill modifier vs. Difficulty Class
Difficulty Class
The DC is a number set by the spell that you must score as a result on your magical skill check to succeed. So to cast a spell with a DC of 15 you must roll a magical skill check total of 15 or better to succeed. A magical skill check that does not succeed may be a Partial Success or Miscast Spell depending upon the results of the die roll and the DC of the spell that was attempted.
A Partial Success is if the magical skill check was within three numbers of the DC then the spell is cast, only with limited results dependant upon the magnitude of failure (within 1, 2 or worse 3). For example if the DC to cast the spell was 15 and the player makes his magical skill check only to roll 13 then he would have a Partial Success. The exact description of the spell effect is left up to GM, but in keeping with the Harry Potter genre, it should be near the effect of the original spell but incomplete, deficient, unfinished, or utterly useless.
A Miscast Spell is when the magical skill check was within three numbers of the Critical Failure (which may change, depending the Critical Modifier of the spell cast). In this case the spell is not cast and the spellcaster suffers some physical damage due to fatigue and spent energies (see below).
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Winded: The character suffers a –1 penalty to effective Strength and Dexterity and magical skill checks, and cannot move all out or charge. A winded character who suffers an additional fatigue result becomes fatigued.
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Fatigued: The character cannot move all out or charge, and suffers a –2 penalty to effective Strength and Dexterity and magical skill checks. A fatigued character who suffers an additional fatigue result becomes exhausted.
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Exhausted: The character is near collapse. Exhausted characters move at half normal speed and suffer a –3 penalty to effective Strength and Dexterity and magical skill checks. An exhausted character who suffers an additional fatigue result falls unconscious (and must recover from it normally, see Damage Conditions).
Recovery
Every 10 minutes of rest, a hero makes a Constitution check (Difficulty 10) to recover from fatigue. Success reduces the character’s fatigue condition by one level (from exhausted to fatigued, from fatigued to winded, winded to normal). A full hour of rest allows any character to completely recover from all fatigue conditions.
Opposed Checks
Some Skill checks are Opposed Checks. An opposed check is a check whose success or failure is determined by comparing the check result to another character's check result. In an opposed check, the higher result succeeds, while the lower result fails. In case of a tie, the higher skill modifier wins. If these scores are the same, roll again to break the tie.
Conditional Modifiers
Some common situations may make a skill easier or harder to use, resulting in a bonus or penalty added to the modifier for the skill checks.
Spell not known: -10
Somebody else’s wand: -4
No wand: -10, and all failures are critical failures
No verbal: -4
Extra time: +2 to skill check for increasing casting time to a Full Round action.
No material Component: -4
Similarities
Spells, especially transfiguration spells, work better when there is some sort of “correspondence” between the original object and the desired effect. The GM can give a bonus of +1 to +2 if the mage is trying to change an object into another object with some sort of similarity - either in size, shape, appearance or name. For example, characters might get a +1 bonus to transfigure a guinea pig into a guinea fowl, or to turn butter into cheese. If an object has multiple “similarities” then these bonuses stack, for example, turning a beetle into a button (similar name, similar size, similar appearance, etc. is a +3 bonus)
Dueling
If two wizards cast spells at each other at the same time, there is a small chance that their “beams” will intersect, nullifying or deflecting one or both spells. Compare the die rolls for both mages, as if they were rolling a contest of spell skills. If the mages tie, both spells are deflected. Roll 1d randomly to determine the direction of scatter. If anyone is along the path of the “beam” they are hit by the errant spell.
Checks Without Rolls
A skill check represents an attempt to accomplish some goal, usually while under some sort of time pressure or distraction. Sometimes, though, a character can use a skill under more favorable conditions and eliminate the luck factor.
Taking 10: When your character is not being threatened or distracted, you may choose to take 10. Instead of rolling 1d20 for the skill check, calculate your result as if you had rolled a 10. For many routine tasks, taking 10 makes them automatically successful. Distractions or threats (such as combat) make it impossible for a character to take 10. In most cases, taking 10 is purely a safety measure -you know (or expect) that an average roll will succceed but fear that a poor roll might fail, so you elect to settle for the average roll (a 10). Taking 10 is especially useful in situations where a particularly high roll wouldn't help.
Automatic Success: If your total bonus on a skill check is equal to or greater than the DC of the spell, you will succeed at that task regardless of what you roll on the die. In this case the GM might not require you to roll and just assume you succeed, since it’s trivial for someone of your skill.
Reading the Spells
Spell Name: This is the common name of the spell.
Activation Word: This is the Verbal Component of the spell.
Skill Used: This is the skill used in the Magical Skill Check.
Casting DC: This is the Difficulty Class number to cast this spell.
Casting Time: Not all spells have this descriptor, and when they do not it is assumed that these spells have a Standard Action casting time.
Critical Modifier: This is the number that is added to 1 to determine what the Critical Failure number is (example: a +3 would make the Critical Failure number 4 or less and the Miscast spell number 5-7).
Saving Throw: This is the Saving Throw used to negate or lessen the effects of the spell.
Area: This is the descriptor of what part of an area is affected by the spell.
Range: How far the spell can be cast.
Target: What, who or how many objects can be affected when the spell is not area.
Duration: How long the spell lasts. Concentration: The spell lasts as long as you concentrate on holding it. Concentrating to maintain a spell does not provoke attacks of opportunity. Anything that could break your concentration when casting a spell can also break your concentration while you’re holding one. You can’t cast another spell while holding the first, unless you have the Practiced Spellcaster feat.
Description: This describes the spells effects, and special effects of the spell.
Components: Usually a wand but sometimes others as well.
