Line of Sight + Mirrors

[BalazarIago]

This weekend, our adventuring party encountered a difficult situation and used ingenuity and creativity to overcome a deadly obstacle.

The room was designed so that the Ogre Zombie could not be reached unless you entered its Threat Zone. Of course, we found this out the hard way. Our second level party had no fighters or clerics, but we were determined.

We decided to use a silver mirror we had found earlier in our adventures and secured it to the end of a quarter staff. The sorcerer send some dancing lights into the room to light it, and our rogue move to the edge of the zombie’s threat zone and positioned the mirror in such a way so that the person behind her could see the zombie. And with the use of spells like Magic Missile, which automatically hit if you can see the target, (I used Molecular Agitation), we were able to kill the Zombie. The DM did require us to roll a Spot check to ensure that we could see the target before casting on it, and it did take a lot out of us to kill it.

My question is along the lines of how valid is it to use a mirror to achieve line of sight. Any comments?

 

[JimAde]

The problem is not Line of Sight. It's Line of Effect. Generally, by the RAW, you need line of effect from yourself to the target. I would definitely let this work if the spell did not require line of effect for some reason (can't think of an example right off hand but I'm sure there are some).

 

[Patryn of Elvenshae]

I would definitely let this work if the spell did not require line of effect for some reason (can't think of an example right off hand but I'm sure there are some).

Many area of effect spells can get around this limitation, by targeting area to which you do have LoE, and then expanding to areas you don't.

For instance, dropping a fireball at the junction around which the rogue was peering would probably still hit the zombie.

 

[JimAde]

Exactly. Because you have both LOS and LOE to the point where the spell is going off. Unfortunately, I can't think of any good spells of that type that a 2nd-level party would have access to. I suspect the GM let it fly because they didn't have any good alternatives (a fine choice, IMO). It's just going to come back to bite him later when the party's 12th-level Warlock wants to hit people with his eldritch spear from 2 blocks away and around the corner.

 

[Patryn of Elvenshae]

Missed the 2nd-level part on the first read-through.

 

[RandomPrecision]

Not RAW, but I'd allow a Sunbeam, for example, to reflect off of a mirror. I don't picture Magic Missile reflecting, however. Alternatively, you could set up a campaign world where mirrors are particularly important, because of their spell-reflecting properties...that could be different.

Of course, at 2nd level, there's not much that I can think of that's light-based that would help here, and that's the prerequisite I'd put on reflecting spells.

 

[TheGogmagog]

Conjuration, Enchantment and illusion spells would usually require line of sight but not line of effect (I think). The evocations would usually require line of effect, but line of sight might be optional (except magic missile).

 

[kjenks]

Main 3.5e FAQ, pp. 33-34:

The rules for targeted spells say you have to be able to
see your target. Does this mean that you can use a mirror to
look around a corner and fire such a spell at a target you
see in a mirror? For example, can you use a mirror to shoot
a magic missile around a corner at your target?

No. First, you must see (or touch) your target to use a
targeted spell. Seeing an image of your target doesn’t suffice.
Second, you must have line of effect to your target (that’s true
for just about every spell), and you don’t have line of effect
through (or around) a corner. If you want to aim a targeted spell
around a corner, you’ll have to peek around the corner at least a
little bit. You still can claim cover from the corner, however.