What is the difference between....

[Rezzin]

Line of sight and line of effect - this is confusing me.

 

[Aloïsius]

Line of sight and line of effect - this is confusing me.

You have a line of sight through a glass windows, but you don't have a line of effect.

 

[MadLetter]

Line of Sight is seeing someone/something. If you don't see them, you don't have Line of Sight.

For Line of Effect you not only have to see them, but the "path" between your target and you must be unobstructed mostly. A glass-wall blocks Line of Effect, but not Line of Sigh.

 

[Ziana]

You don't necessarily need to see someone to have line of effect.

If you know someone is in a completely darkened 20'x20' room, you can toss in a fireball without seeing them, and still damage them.

 

[Tony Vargas]

Mechanically, the main difference in determining the two is that concealment blocks line of sight, but not line of effect. The main difference in dealing with the two is that blocked line of effect generally means you can't do anything to the target, while blocked line of sight just means that you take a penalty to hit and might have to guess which square the target is in.

 

[Harr]

If you can see it, you have line of sight to it.

If you can throw a pebble at it and hit it (even if you have to guess where it is) you have line of effect.

 

[Nifft]

Yup, what they all said. Here it is in short form:

- Glass blocks line of effect.

- Smoke blocks line of sight.

- Walls block both.

Cheers, -- N

 

[mattdm]

- Glass blocks line of effect.

Just to complicate things a bit....

I'm not sure that's true, actually. The PHB says "a transparent wall of magical force", which is considerably different from glass. Is glass considered "solid" even to an effect which is a burst of light? How about a canvas tent wall vs. that light? What about a burst of sound, then?

If this were 3E, I'd probably say "well, the rules say that magic light acts in this weird specific way". In 4E, I'm more inclined to apply common sense about the type of obstruction vs. the effect under consideration (sort of like the rules on page 66 of the DMG about deciding that a gauzy curtain might have a vulerability to fire).

 

[GoLu]

Just to complicate things a bit....

I'm not sure that's true, actually. The PHB says "a transparent wall of magical force", which is considerably different from glass. Is glass considered "solid" even to an effect which is a burst of light? How about a canvas tent wall vs. that light? What about a burst of sound, then?

If this were 3E, I'd probably say "well, the rules say that magic light acts in this weird specific way". In 4E, I'm more inclined to apply common sense about the type of obstruction vs. the effect under consideration (sort of like the rules on page 66 of the DMG about deciding that a gauzy curtain might have a vulerability to fire).

I dunno. What's radiant damage do to transparent things? (Technically, the same as to anything else, with DMs houseruling as they see fit. As you mentioned, there is a strong emphasis on that last part.)