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Parma Magica
Parma Magica roughly corresponds to the concept of spell resistance in D&D. The target of a spell can use Parma Magica to resist the effects of the magic. The resistance succeeds if the target’s
d20 + Parma Magica × 10 + Form
equals or exceeds
casting total + Penetration
Form |
Target’s ranks in Form of spell being resisted. |
Casting Total |
Roll total from spell casting roll. Based on type of spell cast, see below. |
Penetration |
Caster’s ranks in Penetration skill |
Note that unlike D&D spell resistance, the target makes the roll to resist.
Other modifiers:
| Add skill ranks in Faerie Magic to target’s total when they resist faerie spells. |
| Parma Magica will only resist Hermetic spells and other spell-like abilities (indicated with the code "Sp" in d20). It does not defend against extraordinary abilities (Ex) nor supernatural abilities (Su). The DM may override these guidelines based on circumstances. |
Parma Magica (in whole or the Form bonus) can be lowered or suppressed. Lowering Parma is a standard action. The Parma remains down until the beginning of the character's next turn, at which time it automatically returns to normal (unless the character wants to keep it down--as a free action).
Might and Spell Resistance
Creatures (and some humans) in Ars Magica use a Might (magical, divine, faerie, or demonic) attribute to determine resistance to magical effects. The resistance succeeds if the target's
d20 + Might × 2 + Form (if any)
equals or exceeds
casting total + Penetration
As with Parma Magica, Might will only resist Hermetic spells and other spell-like abilities (indicated with the code "Sp" in d20). It does not defend against extraordinary abilities (Ex) nor supernatural abilities (Su). The DM may override these guidelines based on circumstances.
Saving Throws
The DC for saves against a Hermetic spell is calculated as follows:
DC = 10* + spell magnitude + Int
|
spell magnitude |
Calculated by dividing spell level by ten [Note 5] |
|
Int |
Int bonus of caster |
| * For added realism, at the cost of added bookkeeping, instead of using a '10' for this equation, use the actual d20 result from the spellcasting roll. See p. 96, "Variant: Spell Roll" in the DMG for more discussion of this option. | |
Example: Farve casts the spell Transformation of the Ravenous Beast to the Torpid Toad (MuAn 63) on a charging bull. In the ArM rules, the bull would need to make a "Size check" at 9+. In the d20 version, the bull would make a Fort save with a DC of 19 (10 + 6 magnitude + 3 Int bonus).
See more detailed save and roll information in the spell conversion notes I am building.
Spell Foci
To convert to d20, double the ArM bonus conferred by a spell focus.
Maintaining Concentration
A magus must maintain concentration while casting and while maintaining some spells. Use the following table (converted from ArM) to calculate the needed DC for a concentration roll. Use the highest DC applicable in the situation. A botched roll means 1d6 fatigue subdual damage per 10 spell levels in the botched spell.
Task/Situation |
DC |
Walking |
10 |
Running |
25 |
Dodging (applying Dex to AC) |
32 |
Jostled |
17 |
Sudden noise or flash |
17 |
Knocked down |
25 |
Damaged |
32 |
Modifying Spell Range, Target, or Duration
At casting time, a magus can use raw vis to increase the duration or range of a spell to a pre-defined level (indicated in the description by the labels after the slashes). Use 1 pawn of vis per 10 spell levels.
At spell design time (i.e. for spontaneous spells, for example), increasing (or decreasing) spell duration, target or range by one level, adds (or subtracts) 10 to the spell level.
Gestures and Voicing
Normally, all spells must be cast with obvious gestures and verbal components. Use the following charts if the mage chooses to modify these elements.
Voice |
Modifier |
|
Gestures |
Modifier |
|
Booming |
+2 |
|
Vigorous |
+2 |
|
Firm |
0 |
|
Bold |
0 |
|
Soft |
-10 |
|
Subtle |
-4 |
|
None |
-20 |
|
None |
-10 |
Casting Time
| Spell Type | Time |
|
Spontaneous Spell |
Standard action |
|
Formulaic Spell |
Standard action |
|
- casting from text |
1 turn per 10 levels of spell |
|
Ritual Spell |
15 minutes per 10 levels of spell |
|
- casting from text |
30 minutes per 10 levels of spell |
Multiple Casting
Follow this procedure for multiple casting. Only a single given mastered spell can be multiply cast.
- Make a Finesse roll (based on Int) against a DC of 17, with a –2 to the roll per spell being cast.
- Roll casting totals for each spell, with a –2 to the roll per spell being cast.
- See ArM rules for special fatigue loss rules.
Any targeting rolls needed are modified by –2 per the number of discreet targets.
Mastering Spells
Mastering a spell has a slightly different effect in ArM than the feat by the same general name in D&D. Mastered formulaic (and ritual, as a subset) spells confer the following benefits:
|
Have a +2 to Concentration skill checks while casting it. |
|
Can be multiply cast. |
|
Always roll a non-botchable spell casting roll (unless using vis to boost the spell). |
|
Roll one less both die when botches do occur. |
To master a spell, spend experience points (XPs) equal to 50 × spell level. The GM may limit the number of XPs spent in this way based on environmental or situational modifiers. [Note 8]
General Casting Modifiers
Other bonuses:
| Add Affinity skill ranks if appropriate from Magical Affinity feat. |
| Any bonus from Cyclic Magic feat. |
| Any bonus from Special Circumstances feat. |
| +10 to casting total per pawn of raw vis expended. |
Spontaneous Spells
Casting
To cast a spontaneous spell, use the following equation to calculate the roll total:
casting total = d20b + BCB + Technique + Form + Int + CP + SB
d20 |
Always treat as a botchable roll. |
| BCB | Base Casting Bonus from the Hermetic Mage class definition. |
Technique |
Ranks in appropriate technique. |
Form |
Ranks in appropriate form. |
| Int | Intelligence modifier. |
CP |
Check penalty due to any armor being worn or encumbrance. |
SB |
Similarity Bonus. If the mage knows a similar spell (GM consent), and makes a Concentration roll at DC 10, he or she can apply 1/10th of spell level as a bonus. |
Other bonuses:
| +6 for Magical Memory feat, if caster takes a minute to contemplate first. |
The following table summarizes how the roll results should be interpreted:
Mage chooses to take… |
Result |
|
…no fatigue, OR has Mecrurian Magic (take fatigue) |
spell level = casting total ÷ 5 |
|
…1d6 fatigue subdual damage per 10 levels of spell, OR has Díedne Druidic Magic (take no fatigue), OR Faerie Raised Merinita (take no fatigue) |
spell level = casting total ÷ 2 |
Fast-Casting
Fast casting is meant to be a technique that allows a mage to quickly cast some defensive spontaneous spell in response to some magical or physical attack. D&D is less flexible around interrupting another’s action with a defensive one of your own, so this technique may not be as useful in the d20 system.
- To "interrupt" your opponent in the d20 System rules, you must be readied (use the ready action).
- Roll your casting roll as normal, but subtract 10 from the total before dividing the result based on fatigue expenditure. Form and Technique used must be appropriate to attack you are defending against. Botched rolls should have three extra botch dice applied.
- Most fast-cast spells should be interpreted as Momentary. You succeed if your result is at least half the penetration (casting roll + Penetration ranks) of the attacking spell. A roll of 23 defends from one physical attack, 33 from up to three attacks, 43 from any number of known attacks, and 53 from all attacks, known or not.
Formulaic Spells
Casting
To cast a formulaic spell, use the following equation to calculate the roll total:
casting total = d20 + BCB + Technique + Form + Con + CP
d20 |
Treat as a botchable roll based on circumstances (whether mastered, casting from a text, or using raw vis to strengthen a spell). |
| BCB | Base Casting Bonus from the Hermetic Mage class definition. |
Technique |
Ranks in appropriate technique. |
Form |
Ranks in appropriate form. |
| Con | Constitution modifier. |
CP |
Check penalty due to any armor being worn or encumbrance. |
Other bonuses:
| Add Faerie Magic skill ranks if casting a Faerie spell. |
| Any bonus from Method Caster feat(s). |
| With Life Boost feat, add 20 per 1d6 subdual damage taken per magnitude of spell (or per 3d6 HP damage taken). |
The following table summarizes how the results should be interpreted:
Casting total is… |
Result |
|
… ≥ spell level |
Spell succeeds. |
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… ≥ spell level - 20 |
Spell succeeds, but caster takes fatigue subdual damage at 1d6 per 10 levels of the spell. |
|
… < spell level - 20 |
Spell fails. Take fatigue subdual damage at 1d6 per 10 levels of the spell |
When casting from text, spell automatically succeeds if you remain conscious. Double botch dice if casting from a text. If casting total exceeds spell level, no fatigue is taken; otherwise, take 1d6 fatigue subdual damage per 10 levels (as usual) for every 10 points by which you missed the roll.
Ritual Spells
Ritual spells are a sub-type of formulaic spells.
Casting
To cast a ritual spell, use the following equation to calculate the roll total:
casting total = d20 + BCB + Technique + Form + Con + Concentration + CP
d20 |
Treat as a botchable roll based on circumstances (whether mastered, casting from a text, or using raw vis to strengthen a spell). |
| BCB | Base Casting Bonus from the Hermetic Mage class definition. |
Technique |
Ranks in appropriate technique. |
Form |
Ranks in appropriate form. |
| Con | Constitution modifier. |
Concentration |
Ranks (don’t add in Con stat) in Concentration skill |
CP |
Check penalty due to any armor being worn or encumbrance. |
Other bonuses:
| Add Faerie Magic skill ranks if casting a Faerie spell |
| Any bonus from Method Caster feat(s). |
| With Life Boost feat, add 20 per 1d6 subdual damage taken per magnitude of spell (or per 3d6 HP damage taken). |
The following table summarizes how the results should be interpreted:
Casting total is… |
Result |
|
… ≥ spell level |
Spell succeeds, but caster takes fatigue subdual damage at 1d6 per 10 levels of the spell. |
|
… ≥ spell level - 20 |
Spell succeeds, but caster takes fatigue subdual damage at 2d6 per 10 levels of the spell. |
|
… < spell level - 20 |
Take fatigue subdual damage at 2d6 per 10 levels of the spell. |
When casting from text, spell automatically succeeds if you remain conscious. Double botch dice if casting from a text. If casting total exceeds spell level, no fatigue is taken; otherwise, take 1d6 fatigue subdual damage per 10 levels (as usual) for every 10 points by which you missed the roll.