Blindness

[Deepblue706]

When blind, your foes have Total Concealment.

Concealment
To determine whether your target has concealment from your ranged attack, choose a corner of your square. If any line from this corner to any corner of the target’s square passes through a square or border that provides concealment, the target has concealment.

When making a melee attack against an adjacent target, your target has concealment if his space is entirely within an effect that grants concealment. When making a melee attack against a target that isn’t adjacent to you use the rules for determining concealment from ranged attacks.

In addition, some magical effects provide concealment against all attacks, regardless of whether any intervening concealment exists.

Concealment Miss Chance
Concealment gives the subject of a successful attack a 20% chance that the attacker missed because of the concealment. If the attacker hits, the defender must make a miss chance percentile roll to avoid being struck. Multiple concealment conditions do not stack.

Concealment and Hide Checks
You can use concealment to make a Hide check. Without concealment, you usually need cover to make a Hide check.

Total Concealment
If you have line of effect to a target but not line of sight he is considered to have total concealment from you. You can’t attack an opponent that has total concealment, though you can attack into a square that you think he occupies. A successful attack into a square occupied by an enemy with total concealment has a 50% miss chance (instead of the normal 20% miss chance for an opponent with concealment).

You can’t execute an attack of opportunity against an opponent with total concealment, even if you know what square or squares the opponent occupies.

Ignoring Concealment
Concealment isn’t always effective. A shadowy area or darkness doesn’t provide any concealment against an opponent with darkvision. Characters with low-light vision can see clearly for a greater distance with the same light source than other characters. Although invisibility provides total concealment, sighted opponents may still make Spot checks to notice the location of an invisible character. An invisible character gains a +20 bonus on Hide checks if moving, or a +40 bonus on Hide checks when not moving (even though opponents can’t see you, they might be able to figure out where you are from other visual clues).

Varying Degrees of Concealment
Certain situations may provide more or less than typical concealment, and modify the miss chance accordingly.

While what happens when you're fighting with a melee weapon while Blind is fairly obvious, I'm having trouble location the rules for spells. Some spells, such as Fireball, have a radius - others need an exact target. Regardless, some amount of guessing would be necessary - exactly, how would one determine what happens to a Fireball thrown by a blind Wizard? Does he have a 50% of guessing where the blast radius will catch his target? Can he possibly overshoot and hit someone beyond his target? Or, since it's a spell and not an attack, does he not have any chance of failure?

I haven't seen much about ranged weaponry, either. If you miss a target only because of the 50% miss chance, can you possibly hit someone else?

Have I missed something? Is there something in that quote I overlooked? Anyone have any answers or suggestions for me? I would appreciate any help.

[Lochar]

For a ray spell or ranged attack, draw a line between the caster/attacker and the one being shot at. Roll the miss chance. If miss, check to see if there's anyone within 5 or 10' of that line. Roll miss chances until someone is hit, or you reach the end of the line.

--Edit

For radius spells, get a coin, flip it onto the mat and have that as the center of the circle

[Bag_of_Holding]

To use a fireball spell, the caster must determine the distance and height at which the spell is going to burst. You shoot a pea-sized ball of flame to that point, and if the sphere collide with anything else before getting to the space it explodes. It's the specific wording of the spell, so you'll have to know where the target is to use the spell. The miss chance should still apply since you have to take a wild guess as to where your target is standing.

With the range attack, if you attack the wrong square, then I'd say you have 50% chance of hitting that person.

[Shhalahr Windrider]

The standard rules don't call for accidentally hitting a target other than the one for which you are aiming.

For area spells, you generally just determine how far away and how high you want the area to be centered. They'd still aim almost flawlessly, as long as you don't guess at putting it where line of effect would be blocked.

Anything with an attack roll would work just like a normal ranged attack.

For individually targeted spells such as magic missile or daze monster, you have to be able to see the target to use, so blindness shuts those down completely.

[Prometheus]

Yeah. I houserule it as the catapult/splash/shot in a crowd rules for erroneous targeting. Roll 1d8 to decide the direction and it moves in that direction an amount proportional to how far away the target is. I would use 20% rounded up. So any target 25 or less would miss by 5, 30 or further away would miss by 10, 55 or further by 15 etc.

Attacking an invisible creature requires knowing what square it occupies, which requires a spot or listen check. If you are firing at open space, you still have to have some sort of guide or you won't know what is where. If you hear a door open, your friend instruct you, or a battle clashes, you could aim x feet in a certain direction from it, hoping that's the right space. Even if it is, you will still be off your miss chance triggers.

As was said before if it hits anything on the way, that's where it actually goes off.