Line of Sight and mirrors

[Havrik Stoneskimmer]

In my game last week, one of my players (who plays an eladrin mage) declared (half in jest) "When I get back to town, I'm buying a mirror!" with the idea being that he could then use it to fey step around a corner.

Would you allow this in your game? What about other powers that need line-of-sight for targeting? Would you allow a wizard to use a hand mirror as a periscope to target a magic missile? Obviously, you can't cast a spell "through" a mirror, but if all you need is to be able to see your enemy to acquire a target, it seems like this would be permissible, at least from a narrative standpoint, if not a game balance one.

I enjoy and encourage creative ideas, so I'd like to be able to say yes to him, at least under a limited set of circumstances. What you people think about the consequences of this - what can of worms does this open?

 

[Journeymanmage]

The Rules you need to check are:
1. Teleportation: PHB p286
- LoS: ~ Need to see the destination.
- No LoE: ~ You can teleport to a place you can see even if you do not have LoE to it.

2. Specific: LoS / LoE rules: PHB p273

Basically, Yes the mirror 'trick' works.

 

[domino]

It's Line of SIGHT so yeah, I'd allow it. Same as if he were fey stepping through a wall with a window in it.

I'm not sure how it would be terribly unbalancing, especially if he needs to hold the mirror in his hand, it'd be much the same as if he just poked his head around the corner to see his destination. Only with the the risk of sword based head injury.

 

[OnlineDM]

I could see an eladrin living in an area with no other eladrin around, and setting up his house with mirrors all over the place, aimed through small holes in walls and floors to allow for quick transportation from any place in the house to any other place in the house. Wow, that sounds like an incredibly fun thing to build!

 

[Saeviomagy]

In my game last week, one of my players (who plays an eladrin mage) declared (half in jest) "When I get back to town, I'm buying a mirror!" with the idea being that he could then use it to fey step around a corner.

...
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Technically all those solutions work just fine without a mirror - because line of sight and effect are determined from any corner of the square you occupy, as long as one corner of your square coincides with the corner, you can teleport around it.

Similarly foes can still attack you from range around such a corner, they just suffer the penalty of improved cover (which you don't).

The only way that the mirror is going to change anything is if the eladrin mage hands it to hover at a corner that is more than 1 square away from him.

As others have said teleport requires only line of sight, not line of effect, teleportations are unique amongst powers in that this tactic works with them. Pretty much nothing else will.

 

[Mengu]

I'd allow it if it came up that there was a mirror on a wall or something.

Technically, if you're at a corner, you can see everything you would be able to see with a hand mirror, just have to lean over a smidge. The hand mirror trick is only useful if you're hiding and trying to not show yourself, and even then the reflection can be seen. So it's just fluff. Doesn't seem harmful.

However, through my magic mirror, I see 7 years of bad luck the first time the character takes a fall.

Edit: and Saeviomagy beat me to the punch.

 

[Havrik Stoneskimmer]

I was thinking about the mage hand trick too, or perhaps a juryrigged periscope.

But I had forgotten about line of effect being needed for almost all powers, so I guess this is less of a DM's judgment thing than I had originally thought. I suppose teleportation is one of the only things where this would come into play (and maybe the rare "an ally you can see" power).

Cool - I'm glad my player thought about this. I'll definitely allow it if he finds a clever point to use it.

 

[ppaladin123]

Maybe he can tie the mirror to his familiar.

 

[Nork]

Make it a fairly cheap wondrous item.

Maybe one that was allowed to have some fairly liberal interpretations of interactions with mage hand.

 

[delericho]

It's Line of SIGHT so yeah, I'd allow it.

Does invisibility break line of sight, then?