In 2014 Magic ruling made the most use of Dynamic Difficulty which was later removed
Afterwards the magic ruling in system was adjusted to account for this as well as to keep magic users from becoming too powerful as well, so a base difficulty was kept in for magic, but for no where else.
After some consideration especially as the system was moving towards the idea that there should be no difference between mundane actions and those deemed magical/psi in order to try and balance all actions and afford the opportunity for any theme of character to be doable within the game here.
The goal was to streamline a bunch of ruling as well as solve the issue where some skills were way too powerful, and some rules had some uneeded bloat.
The reasoning is covered here: http://vaxia.org/forums/discussion-combat-mechanics-tweak-magic/psi
The sections below were how magic ruling was handle until the above proposed changes.
All spellcasting, whether it's arcane magic, psionics, divine intervention, etc., uses INT and SPI along with the appropriate skill.
Base difficulty for spellcasting is 25 in almost all cases, with only a couple of exceptions (noted below). As always, additional circumstance modifiers may apply, just like any other roll. Otherwise, magic is a simple two-trait ruling.
When you're casting against a being, say in combat, the target's defensive Stats get added to the mix. What stat they defend with will depend on the nature of the spell - a fireball goes against DEX and END, an attempt to read someone's thoughts goes against INT and SPI. In both cases, the casting mage's INT is paired off against the target's DEX or INT, and their SPI goes against END or SPI.
You simply add the spell's base difficulty (typically 25) to the defending stat. This is the stat, not the mights, since most skills used in combat can't work against magic directly. If a fighter has DEX 30 and END 40, the mage casting the difficulty-25 fireball is now up against difficulties of 55 and 65, respectively. See the Magic vs Mundane Combat page for how to handle opposed maneuvers like blocking or dodging.
If a mage fails to affect their target, don't automatically treat it as a failure. In those cases, check the mage's rolls against the base spell difficulty - if they succeeded in casting the spell but didn't affect their target, the spell still went off, the target simply resisted (or successfully dodged, blocked, etc), and your narrative should reflect that.
To help understand the impact this'll have in practice, let's look at how this compares with mundane combat. The base difficulty for the spell is effectively replacing the target's combat skill for passive defense. A fighter would be up against stat + skill when attacking, a mage is up against stat + spell difficulty instead.
In the rare case that a target has a skill specifically to deflect or endure magical effects, that skill can be added to the overall difficulties where appropriate. Most standard combat skills do NOT fall into this category, it would typically need to be a skill dedicated to magical resistance or avoidance.
While it may not be called this in the skill, metamagic is any form of magic that affects other magical effects.
As its own skill, metamagic typically allows things like draining or empowering other spells and effects, creating "dead magic" zones, and redirecting or reshaping the spells of others. It typically doesn't generate any effect on its own, it needs another spell or magical effect to operate off of.
Treat this similarly to combat magic, with the INT and SPI might of the caster whose spell is being targeted as the difficulties for the second part of the ruling.
From a system standpoint, the biggest difference with metamagic is that it starts at a base difficulty of 45, not 25, like most magic. The rationale is that metamagic is simply that much more intricate than other forms of magic because it's tinkering with the fabric of magic itself, magically. If that has your head spinning, just remember that metamagic is typically +20 difficulty over normal magic
If the metamage succeeds, the raw Points Produced can be added to bolster or weaken the spell directly, depending on the intent of the effect. If a metamage wishes to change the nature of the effect (fire to ice, for instance) or redirect it somewhere else, they need to produce as many PP as the original caster in order to succeed. You can choose if you wish to allow a partial success or not.
Otherwise, it works a lot like blocking or parrying in mundane combat: a metamage trying to affect another character's spell rolls their mights versus 45 + the opposing mage's INT and SPI, respectively (the target's magic skill doesn't apply). If they bolster another mage's spell, the metamage's PP add directly into the original caster's PP for a combined effect. Similarly, if the metamage drains the spell, their PP subtracts from the original mage's PP to cast the spell, reducing the effect.
If a metamage only partially succeeds on something like redirecting another spell, it won't likely hit its original target, but it won't hit whatever target the metamage was directing it toward, either. How that plays out exactly is up to you to describe.
Mundane vs Magic Combat
So we've covered magic damage, and mundane combat maneuvers, but what happens when they wind up at odds with one another?
If a mage flings a spell at a warrior who's attacking the mage, nothing changes: the warrior does damage using the mage's stats as her target, and vice versa. But if the warrior raises her shield to block a fireball, how do we calculate the result?
The answer is to rule it in two parts. First, rule the spell as normal, accounting for the possible shift in resisting stats (a mage targeting a blocking opponent adds their STR and END stats to their ruling, rather than the usual DEX and END). Only the stats are accounted for here, even though they're actively defending.
Second, the person blocking or dodging the spell rolls their combat Mights versus the mage's INT and SPI Mights (INT roughly equates to speed and accuracy, while SPI is the measure of power and force). Any points they produce subtract from the mage's PP for the spell, directly reducing the damage taken.
Magic vs Mundane in the Dice Ruler
The dice ruler doesn't include a magic-vs-mundane option, so you'll be using a combination of the Magic Ruling and the Multi-Trait Ruling : Two-Trait Ruling selections.
Rule the magic as normal. Then, enter the defender's appropriate Mights into the Two-Trait Ruling section, with the mage's INT and SPI Mights as the difficulties (see below). That will give you the defender's PP. The casting mage's target stats may also change:
If the defender is trying to dodge...
- Their DEX Might is opposed by the mage's INT Might
- Their END Might is opposed by the mage's SPI Might
If the defender is trying to block...
- Their STR Might is opposed by the mage's INT Might
- Their END Might is opposed by the mage's SPI Might
It is very rare that a spell can be parried, but in such a case (like an ice mage flinging deadly icicles at a target):
- The defender's DEX Might is opposed by the mage's INT Might
- The defender's STR Might is opposed by the mage's SPI Might
NOTE: Some spells, like mental effects and others that target SPI instead, cannot be blocked, dodged or parried. Someone rolling a skill specifically designed to resist such spells can do so via the One-Trait Ruling option, and the PP subtract as described above.
For the mage's PP, use the Magic tab in the Helper, as normal. They still use the spell's base difficulty plus the target stat (and any relevant magic-resisting skill, even though the target may be using a combat skill to dodge).