D&D General "that you can see", "line of sight", glass, mirrors, ~clairvoyance, blindsight, and anything else.

[Oofta]

If someone wanted to use a mirror to target a medusa with a magic missile I'm not going to say no.

If you have a mirror around a medusa the best tactic is to do a light cantrip and get it to look at it's own reflection.

If the medusa sees itself reflected on a polished surface within 30 feet of it and in an area of bright light, the medusa is, due to its curse, affected by its own gaze.​

 

[ad_hoc]

If you have a mirror around a medusa the best tactic is to do a light cantrip and get it to look at it's own reflection.

If the medusa sees itself reflected on a polished surface within 30 feet of it and in an area of bright light, the medusa is, due to its curse, affected by its own gaze.​

Well, I'm not going to stop the player and explain to them that their idea is bad and what the best tactic actually is.

 

[greg kaye]

If you use a mirror then the you would be targeting the image in the mirror not the actual creature. ...

If you use a mirror when targetting a medusa, you'd be just as vulnerable as ever. You can see the medusa (for targetting the medusa) and can see it's eyes (for being targeted yourself).

 

[fluffybunbunkittens]

Wait...

Walls, trees, creatures, and other obstacles can provide cover during combat

A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.

Holding up a blanket makes you untargettable? If the GM objects, get a thicker blanket? How thick does the blanket have to be to count as an obstacle? How about carrying a wheelbarrow in front of you? I'd call that an obstacle. So the line must be somewhere between them, at the worst.

 

[Umbran]

If you use a mirror when targetting a medusa, you'd be just as vulnerable as ever. You can see the medusa (for targetting the medusa) and can see it's eyes (for being targeted yourself).

Yep. If you have line of sight on it, it has line of sight on you.

"Why are there all these statues here of people with mirrors crouching by walls?"

 

[Oofta]

If you use a mirror when targetting a medusa, you'd be just as vulnerable as ever. You can see the medusa (for targetting the medusa) and can see it's eyes (for being targeted yourself).
View attachment 286164

True, but you can also close your eyes or avert your gaze. In addition, you have to be within 30 feet for the gaze to have effect. With a little planning, luck and perhaps a mage hand it's doable.

 

[the Jester]

The only way around this would be to rule that the setting's physics prevent the transmission of magic through any intervening solid barrier; but that opens up a whole other list of in-setting headaches and inconsistencies.

This is exactly what the rules say- you can't cast a spell through an intervening barrier. Whether that barrier is transparent is irrelevant.

I should ask: are there no spells left in 5e that in fact allow a caster to shoot blind e.g. to cast it behind a closed door just in case there's something there?

Generally only scrying or teleportation effects bypass by the barrier restriction, but there are spells that target "a creature in range" rather than "a creature in range that you can see".

 

[Oofta]

This is exactly what the rules say- you can't cast a spell through an intervening barrier. Whether that barrier is transparent is irrelevant.


Generally only scrying or teleportation effects bypass by the barrier restriction, but there are spells that target "a creature in range" rather than "a creature in range that you can see".

Teleport and scrying have a target of self.

 

[Oofta]

Wait...




Holding up a blanket makes you untargettable? If the GM objects, get a thicker blanket? How thick does the blanket have to be to count as an obstacle? How about carrying a wheelbarrow in front of you? I'd call that an obstacle. So the line must be somewhere between them, at the worst.

How else do you think rogues take no damage if they're successful on dex saves?

 

[Lanefan]

This is exactly what the rules say- you can't cast a spell through an intervening barrier. Whether that barrier is transparent is irrelevant.

Generally only scrying or teleportation effects bypass by the barrier restriction, but there are spells that target "a creature in range" rather than "a creature in range that you can see".

That doesn't play nice with spells like Locate Object, where even though the target is technically "self" there's still some sort of magical effect that pings the object(s), which can be behind all sorts of barriers and obstructions.

To be consistent with the no-barriers rule Locate Object should only find objects you could in theory already see, assuming lighting conditions allowed, and this would render the spell close to useless.