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View Full Version : Can Nystul's Magic Aura foil Arcane Sight vs. Invisibility?



Curmudgeon
2007-10-11, 05:46 PM
Here's the scenario:

Say a sneaky character wants to lie in wait for someone who has Arcane Sight on full-time due to Permanency. They've got a Ring of Invisibility, which can be rendered undetectable to the Arcane Sight via Nystul's Magic Aura. But what about the actual Invisibility effect on the sneaky character? Nystul's Magic Aura only targets objects.

What if the sneaky character has total cover due to an invisible tower shield that itself has Nystul's Magic Aura to read as non-magical? The tower shield should block Arcane Sight against the sneaky character, because only targeted spells can get through a tower shield.

The plan is to get a lot of low-level sneaky characters ready to pounce on one high-level spellcaster, with off-stage support from a caster with a couple of wands: Extended Invisibility and Nystul's Magic Aura. At low levels we can't expect large numbers of ambushers to make adequate Hide checks. But if they can be invisible and not detect as magical to the mark's Arcane Sight I think the ambush has a decent chance of working.

Thoughts?

Jasdoif
2007-10-11, 06:06 PM
Hmm. Arcane Sight says it detects auras that are in your sight. If you're invisible, you're not in sight; does that mean your magical auras aren't in sight either? If they're not, then Arcane Sight is of no use against your invisibility.

deadseashoals
2007-10-11, 06:39 PM
Hmm. Arcane Sight says it detects auras that are in your sight. If you're invisible, you're not in sight; does that mean your magical auras aren't in sight either? If they're not, then Arcane Sight is of no use against your invisibility.

That's how I always saw it. Detect magic also has a clause about pinpointing auras within your line of sight FWIW.

Curmudgeon
2007-10-11, 06:50 PM
I always assumed that even if you're invisible, your magical auras are present for Detect Magic and Arcane Sight to "see".

So you think that Arcane Sight doesn't work where See Invisiblity will? SI is a lower-level spell.

Arbitrarity
2007-10-11, 06:57 PM
Actually, line of sight is defined, and invisibility does not null it. Sight, on the other hand, is a different story, as it is not defined. It appears detect magic, in three rounds, will pinpoint invisible creatures, but arcane sight will not? Given that arcane sight is "similar to detect magic", I propose that this is precedent for "sight" implying line of sight, which is defined on PHB 139.

....
2007-10-11, 07:07 PM
I'd say that the way spells like arcane sight and detect magic let you see invisible things is by you focusing on an outline of magical energy surrounding them.

Since Nystul's Magic Aura makes this aura disappear, I'd say it would nullify the other spells ability to locate invisible people.

But I'm not sure about the "it only affects objects" thing. I'd have to read the spell and think about it.

I figure its really up to the DM, in the end.

Chronos
2007-10-11, 07:18 PM
So you think that Arcane Sight doesn't work where See Invisiblity will? SI is a lower-level spell.That needn't imply anything. Meteor Swarm also won't work where See Invisibility will. The spells are designed for different purposes.

deadseashoals
2007-10-11, 07:26 PM
Actually, line of sight is defined, and invisibility does not null it. Sight, on the other hand, is a different story, as it is not defined. It appears detect magic, in three rounds, will pinpoint invisible creatures, but arcane sight will not? Given that arcane sight is "similar to detect magic", I propose that this is precedent for "sight" implying line of sight, which is defined on PHB 139.

Invisibility does block line of sight, see page 152 of the PHB under total concealment.

Curmudgeon
2007-10-11, 07:39 PM
Invisibility does block line of sight, see page 152 of the PHB under total concealment. Certainly. Invisibility will block line of sight to the creature, as specified.

The question is: Does Invisibility block line of sight to the creature's aura? This isn't specified.

Arbitrarity
2007-10-11, 07:42 PM
Curses!

This seems illogical, but apparently, one cannot detect objects under the effects of a spell, if they are invisible (and/or affected by the invisibility spell), or, apparently, covered in an illusion.

Jasdoif
2007-10-11, 07:42 PM
Wait a minute....
At low levels we can't expect large numbers of ambushers to make adequate Hide checks.Is making Move Silently checks, with a -10 armor check penalty from a tower shield, going to be any easier?

Curmudgeon
2007-10-11, 07:47 PM
Wait a minute....Is making Move Silently checks, with a -10 armor check penalty from a tower shield, going to be any easier? Nope, which is why they're going to arrive early and just wait for the target to arrive. You don't need to make Move Silently checks if you don't move.

Jasdoif
2007-10-11, 07:58 PM
The ultimate problem with the tower shield plan is that it appears unnecessary either way. If invisibility blocks arcane sight, then even without the tower shield they won't be detected. If invisibility doesn't block it, then the invisible tower shield won't block arcane sight from reading the invisibility effect on the characters.



Nope, which is why they're going to arrive early and just wait for the target to arrive. You don't need to make Move Silently checks if you don't move.Target's coming to them, huh?

Well...do they really need invisibility active the whole time, or are there sufficient places to hide that would grant (total) concealment/cover? If you have the rings magic aura'd, the only time the characters would register on arcane sight is when the invisibility effect is active. If they use invisibility to get into place beforehand, then don't renew the effect....