[Reaver]

The way I had it explained to me, was that with indirect spells, you are creating a discharge that extends from you to the target, be that a gout of flame, an arc of electricity, or a stream of acid. In the case of AOE (fireball, acid wave, Etc), it still starts at you, then streaks to the target and explodes.

This has tactical implications to it. Take a narrow hallway with an invisible/hidden attacker. With the indirect rules outlined above, the mage could target the fall wall, and fill the hallway with fire, possibly hitting the hidden attacker... much like someone could spray the hallway with machinegun or shotgun fire and hit the attacker.

[Mirikon]

Direct spells autohit, but require you to see the target. Even if you throw a Manaball into a room small enough that everyone inside is in the radius, if you don't have line of sight on everyone (you can use astral perception, but you'll be eating that -2 penalty), anyone you don't see (like the guy hiding behind the door) is completely unaffected.

Indirect spells require a to hit roll, which means they're subject to visibility modifiers, cover, and the like. However, you don't need to be able to see individuals to affect them with indirect spells. You just have to see the target area. For single-target spells that doesn't mean much, but for AoE, that means you drop a fireball in the small room from above, and everyone gets roasted.

Direct spells also only work on living creatures, while indirect can affect objects.

[PiXeL01]

I’m going to be “that guy” on this one and ask you to point out where it says it is a to hit roll subject to all those modifiers, Mirikon.
The Indirect description simply says it is an opposed test, though the defender uses the same attributes as versus a mundane attack.

How did SR4 describe it? Anyone able to quote?

[Kiirnodel]

There are a couple things in play here. First, the rules on Spellcasting actually state that Visibility modifiers applies to all spells that are targeted visually.

Spellcasting by visual targeting is subject to normal visibility modifiers.

And the rules for Good/Partial Cover also specifically note that the bonus to the defense test applies to Spellcasting. Although, oddly enough, Good Cover says "Spellcasting" while Partial cover specifically only calls out "Indirect Combat Spells" which could have other implications.

None of the other defense modifiers make this call out though. However, this doesn't necessarily mean that they wouldn't likewise apply... For example, the bonus for Running (+2 bonus on their Defense test) seems like it could still apply. The roll to avoid the spell is still a Defense roll after all...

[PiXeL01]

Thank you.
I knew there was a reason for why I treated it as a ranged attack from the beginning.
The cover defense entries are found on p. 190 CRB

[Mirikon]

And the rules for Good/Partial Cover also specifically note that the bonus to the defense test applies to Spellcasting. Although, oddly enough, Good Cover says "Spellcasting" while Partial cover specifically only calls out "Indirect Combat Spells" which could have other implications.

Well, good cover would be an elf ducking behind a car and popping up over the hood to take a shot. Partial cover would be a troll caught in the open with nothing but a telephone pole to use for cover, but it is still something else between him and incoming lead, so...

[Kiirnodel]

And the rules for Good/Partial Cover also specifically note that the bonus to the defense test applies to Spellcasting. Although, oddly enough, Good Cover says "Spellcasting" while Partial cover specifically only calls out "Indirect Combat Spells" which could have other implications.

Well, good cover would be an elf ducking behind a car and popping up over the hood to take a shot. Partial cover would be a troll caught in the open with nothing but a telephone pole to use for cover, but it is still something else between him and incoming lead, so...

Right... but is the implication that Good Cover gives the +4 when defending against all spells? Does someone resisting a Manabolt get +4 dice because of taking Good Cover? What about Control Thoughts? Invisibility? There are some weird implications if we apply it unilaterally...

[PiXeL01]

It should only be indirect spells and possibly damaging manipulation spells in my humble opinion

[ShadowcatX]

In world good cover could block enough of a person's aura from being seen to give them an edge in defending against magic, while partial cover does not.

More likely it is just poorly written. Can anyone from the errata team chime in?

[firebug]

Hmm, after a second thought, I think the logic is just that they do block visibility.  Which is kind of the idea of the bonus that cover gives; after all, being behind a steel parapet is the same bonus as being behind one made of cardboard in a school.  It's easier for the defender because you can't see their whole body.  This is why the book specifies that someone totally behind cover also benefits from the blindfire penalty, because the cover stops you from seeing them.  If you pay close attention to the wording for cover, you'll notice what bonus you get is based entirely on how much of your body is obscured from the attacker, reinforcing that it's about visibility.

Because spells need Line of Sight and are affected by anything that affects vision, cover is a vision effect, and so applies to all spells under the basic idea of "it's harder to hit what is harder to see".

If you want to assume the way it's written is intentional, it's possible that the writer felt partial cover was too insignificant to count as visual interference, and so only applied it to the physical projectile spells (indirect combat spells).

[Rosa]

While I agree that the standard modifiers apply to indirect combat spells, since they are handled as ranged combat tests  ( SR4 20TH page 203-4 ), SR4 is less vague about this fortunately, direct combat spells are resistance tests not defense tests as are in fact almost all other spells are resistance tests not defense tests. In essence that means that anything that adds dice to your defense test only applies to defense against indirect spells as they are the only ones you defend against. All other spells can only be resisted and thus the only source that can add dice to the test is the spell defense skill ( confusing that they don't stay consistent with the terminology and SR5 is by far the worst edition in that regard that I know of ) as well as the magical guard critter power.

It makes total sense to impose negative modifiers for visibility on the spellcasting test on spells that require Los to hit another target like direct combat spells and for example mental manipulation spells, but that's it. As Mirikon said, if they can see you, those spells auto hit, there is no defense test just a resistance test against the effect the magician is trying to achieve,  so of course being in cover will not suddenly make you better at seeing through illusions like invisibility, the very thought is absurd and would lead to some truly absurd situations in the game.

This is also the reason why the spell defense skill is a must have for all team player magicians as it is the best defensive aid against hostile magic.

[firebug]

I can see your logic.  I still believe that cover is a visual modifier, and so should apply to anything that concealment and darkness would apply to.  You're right--  It doesn't make a lot of sense that being partially behind a wall would make it easier to resist believing an illusion.  But neither does it make a lot of sense that if an area is dark, it's harder for you to cast Stealth.

But it does, because all spells require Line of Sight, and as the book says, "Spellcasting by visual targeting is subject to normal visibility modifiers." (page 281, Step 2: Choose The Target).  Someone can argue that seeing any part of someone's aura is as good as seeing all of it, but that's conjecture--  How casting a spell works in-universe is not so defined, as far as I know.  After all, if it were that binary, what would the Spellcasting roll or the Resistance roll represent?  The same way that you can fail to cast a spell, and that someone can resist it completely, I think how much aura you are able to aim your magic at affects the overall outcome of the spell.  Maybe when you have LOS to less of their aura, you aren't able to get as much of your mojo into them, which is represented by penalties to your roll or bonuses to theirs.  The dice are abstractions after all.

[Rosa]

Yes that's why I said that visibility modifiers should apply to the spellcasting roll as negative dice and not to the person resisting the spell as positive modifiers to the resistance roll and that includes bonus dice for being in cover. The only time cover would give you bonus to your roll would be against indirect combat as that is an actual ranged attack.

As far as it being harder to cast stealth in darkness you're right in so far as the writers should have put self/Los in for spells like that in stead of just Los because you should always be able to target yourself, but if you wanna cast it on your buddy a few meters away from you it makes sense to use visibility modifiers.

[firebug]

There's no real difference between "bonus to defender" and "penalty to attacker" though outside of edge cases, which is why Reach can be either one.  If "it's a bonus to the defender" is the reason why you think cover shouldn't be applicable by darkness should, despite them both being different ways to say "your ability to see your entire target is hampered", then I think you're approaching things from the wrong angle.

The reason cover provides a bonus to defenders is probably for AoE attacks, as you're more likely to hit a group where only some of them are behind cover (or the amount of cover varies) than you are to be firing into an area that is pockets of pitch-black and almost pitch-black to hit multiple targets--  Such an area would probably be ruled as either complete darkness or dim light over the entire zone.  This way the attacker can roll once and the hits can be compared to each defender's hits.  This is the same logic used to determine whether any modifier to attacks should be an attacker penalty or a defender bonus; if it's a condition that's applied to each target individually (like cover) it's a bonus to their defense.  If it's a condition that's applied to only the attacker or to the entire area (like darkness) then it's an attacker penalty.

[brombur]

Got alot more discussion on this than was expected.

I say that anything impacting the caster's roll is a no go, after all they just need to see the target to know where to throw the spell. the Defender then gets chance to avoid it the same as a gunshot so any bonuses they earn are their to use. Also part of my issue was that in the Runnign rules it says that a running target inflicts a -2 penalty to the shooter but this appears no where else and is not on the attack mod table later in the book. I can only assume this line is written in error and that running just provides a defense test bonus to the target.

Ultimately I think with Drain being tied to the same roll as hitting your target you can't be adjusting the mages pool at all, except for the previously mentioned vision mods. its the best you can get unless you want to house rule it an separate out the too rolls.