Continuous Detect Magic

[Quidam]

Having just levelled my warlock to 2nd, I'm thinking about creative uses for detect magic. The fact that it can penetrate stone and wood and even some metal can make it useful for scouting.

I was looking at the rules for lingering auras and was considering how it might be used to track someone. Since you'd have to stop every 60' for 18s, you couldn't go very fast, but if the aura were strong enough it seems like you could just follow their trail. Am I missing something there?

 

[kenobi65]

I was looking at the rules for lingering auras and was considering how it might be used to track someone. Since you'd have to stop every 60' for 18s, you couldn't go very fast, but if the aura were strong enough it seems like you could just follow their trail. Am I missing something there?

Other than the fact that you are, indeed, stopping for 18 seconds every 60 feet, no, you're not missing anything.

This thus assumes that your movement is something like this:
Round 1) Move 60'
Round 2) Concentrate
Round 3) Concentrate
Round 4) Concentrate

That gives you an average per-round movement of 15'. Assuming your quarry isn't stopping, he'll have an average per-round movement of at least 40' (and that assumes either short legs or armor). He'll quickly outdistance you, and unless he's hauling around extremely powerful magic items, those "lingering auras" you're tracking will fade quickly -- most magic items are going to have no stronger than "moderate" auras, which means that those auras will only linger, on average, 3.5 minutes.

Thus, it's likely that you'll lose him fairly quickly, especially if he had any kind of a lead on you when you started. If the "trail" is more than 6 minutes old, you'll likely have nothing at all.

 

[HeavenShallBurn]

There's an item in the Eberron setting that basically does this, lets you view the trace auras of living creatures who passed through an area. Called Inquisitive Goggles, perhaps you could modify one of the ideas there to use. Like was said using detect magic straight up cuts your speed to a crawl and the auras fade to fast to be much use, but if you upped the length of time auras hung around as traces it could work. maybe dc15+the number of days since the creature passed through the area to follow a trace aura?

 

[Infiniti2000]

This thus assumes that your movement is something like this:
Round 1) Move 60'
Round 2) Concentrate
Round 3) Concentrate
Round 4) Concentrate

Not quite. Detect Magic requires a standard action to concentrate and thus at most the movement will be 30ft per round (or whatever the speed is). Assuming you need to stop for the 3 rounds, you could:

1. Move 30ft, stop, cast detect magic (1st round of use)
2. concentrate
3. concentrate (3rd round) and move another 30ft.
4. concentrate
5. concentrate
6. concentrate and move another 30ft.
...

 

[Bad Paper]

Why would you have to stop at all? Maybe if there were another trail of magic, you'd have to study the divergence, but otherwise, you can just detect the presence of magic. Hence,

1. concentrate and move
2. concentrate and move
3. concentrate and move
et cetera

 

[kenobi65]

Why would you have to stop at all? Maybe if there were another trail of magic, you'd have to study the divergence, but otherwise, you can just detect the presence of magic. Hence,

1. concentrate and move
2. concentrate and move
3. concentrate and move
et cetera

If you're out in BFE wilderness, where you're not encountering other trails, then, yeah, that would work, I suppose. You're still probably moving more slowly than your quarry, and you'll run into the same problem as before, just not as quickly.

 

[kenobi65]

Not quite. Detect Magic requires a standard action to concentrate and thus at most the movement will be 30ft per round (or whatever the speed is). Assuming you need to stop for the 3 rounds, you could:

1. Move 30ft, stop, cast detect magic (1st round of use)
2. concentrate
3. concentrate (3rd round) and move another 30ft.
4. concentrate
5. concentrate
6. concentrate and move another 30ft.
...

If you're a regular spellcaster doing this trick, yeah, you're right.

The OP was talking about doing it with a warlock, who could turn the ability on at will, and thus would not need to continually keep concentrating in order to maintain it.

 

[Infiniti2000]

The OP was talking about doing it with a warlock, who could turn the ability on at will, and thus would not need to continually keep concentrating in order to maintain it.

He can cast it as often as he wishes, so he could do the following:

1. Move 30ft, cast detect magic (or vice versa)
2. goto 1

But, then he would only ever get presence or absence of magical auras. If that's the goal, then okay. But, he certainly needs to concentrate each round if he wants more than just presence/absence of auras. He could move, yes, but then he affects a different area each round.

 

[Infiniti2000]

Why would you have to stop at all?

It completely depends on how wide of an area you want to check (only one such area per round) and what you want to get out of the area (only presence/absence or more).

 

[Abisashi]

If you know there are no other trails around, you can follow by just checking for existence. If it no longer exists in front of you, it must have turned, which would require a few rounds to figure out which direction.

If the warlock tracking you doesn't realise that you can generate a second such trail, you just do a right turn at some point and send a minion on ahead to make a second trail; the warlock will just detect that a trail is still ahead of him, and have no idea you split up. Given the warlock's speed, the minion is unlikely to be in any danger.