Detect: instantaneous or continuing?

[Mr_Sandman]

When putting the Costs Fatigue limitation on Detect, would you treat Detect as having an instantaneous effect or continuing effect? More broadly, is Detect something that can continue over time, to allow someone using it to track something's movement or aim a ranged attack, or does it just give a 'snapshot'?

The description of Detect in Characters says it requires a second of concentration and a sense roll, and does not give a time period for how long it works after that. That seems to imply to me that it should be treated as instantaneous. Otherwise, it could be 'left on', to avoid the need for that second of concentration.

Psionic Powers says that Precise turns Detect into a sense that can be used for targeting, like vision. In that case, how should it interact with an Aim maneuver? If you have spend a turn Concentrating to Detect, does that mean you you can't Aim using Detect? You Concentrate for one turn, then Attack the next?

Using Reflexive seems like a way around it, to avoid the need for a turn of concentration. However, Reflexive includes a -4 to success rolls to activate, I assume this would apply to the sense roll on Detect, but would that be necessary to make each turn of Aim?

How would you handle it?

[johndallman]

Originally Posted by Mr_Sandman

When putting the Costs Fatigue limitation on Detect, would you treat Detect as having an instantaneous effect or continuing effect?

I'd treat it as activating for one minute, as per the description under Costs Fatigue on B111.

More broadly, is Detect something that can continue over time, to allow someone using it to track something's movement or aim a ranged attack, or does it just give a 'snapshot'?

I've always seen it treated as continuing over time. I have had a character with a Detect that cost fatigue, and found that buying off that limitation was very worthwhile.

The description of Detect in Characters says it requires a second of concentration and a sense roll, and does not give a time period for how long it works after that. That seems to imply to me that it should be treated as instantaneous. Otherwise, it could be 'left on', to avoid the need for that second of concentration.

... but goes down as soon as you concentrate on anything else, including mundane problems.

Psionic Powers says that Precise turns Detect into a sense that can be used for targeting, like vision. In that case, how should it interact with an Aim maneuver? If you have spend a turn Concentrating to Detect, does that mean you you can't Aim using Detect? You Concentrate for one turn, then Attack the next?

The problem goes away if Detect lasts a while.

Using Reflexive seems like a way around it, to avoid the need for a turn of concentration. However, Reflexive includes a -4 to success rolls to activate, I assume this would apply to the sense roll on Detect, but would that be necessary to make each turn of Aim?

You really don't want a Reflexive Detect that costs fatigue. That's a route to running out of fatigue and taking hit points.

[NineDaysDead]

Originally Posted by Mr_Sandman

Using Reflexive seems like a way around it, to avoid the need for a turn of concentration. However, Reflexive includes a -4 to success rolls to activate, I assume this would apply to the sense roll on Detect,

Detect applies to activation rolls, not sense rolls:

Originally Posted by Kromm

The roll at -4 is the activation roll. A Sense roll isn't an activation roll . . . what Reflexive does here is count as a level of Reduced Time (so you don't need actions to use your senses, like a Concentrate maneuver to attempt a Vision roll to spot a distant target) and let the sense wake you up. I agree that the distinction between activation and use rolls in GURPS leaves something to be desired, but they are different.

[Mr_Sandman]

Originally Posted by johndallman

I'd treat it as activating for one minute, as per the description under Costs Fatigue on B111.

I've always seen it treated as continuing over time. I have had a character with a Detect that cost fatigue, and found that buying off that limitation was very worthwhile.

... but goes down as soon as you concentrate on anything else, including mundane problems.

The problem goes away if Detect lasts a while.

You really don't want a Reflexive Detect that costs fatigue. That's a route to running out of fatigue and taking hit points.

It's true that assuming Detect is a continuous effect makes it much less cumbersome to use. I'm not GMing the campaign this character is for though, so I didn't want to make any assumptions. Also, I'm noodling around with the consequences of treating it one way or the other, and I suppose I'm just curious about the 'original intent'.

I suppose Costs Fatigue and Reflexive are a dangerous combination. Part of me kind of likes the idea of a character that has an Achilles' heel like that. I could see giving a powerful NPC that combination, and seeing if the PC figure it out and plan a way to take him down with repeated surprise attacks.

Originally Posted by NineDaysDead

Detect applies to activation rolls, not sense rolls:

Thanks for the Kromm-quote on that. It makes Reflexive more useful on Detect.

[johndallman]

Originally Posted by Mr_Sandman

I suppose Costs Fatigue and Reflexive are a dangerous combination. Part of me kind of likes the idea of a character that has an Achilles' heel like that. I could see giving a powerful NPC that combination, and seeing if the PC figure it out and plan a way to take him down with repeated surprise attacks.

It may not take any figuring out. If the NPC has Detect (Something the PC has, Reflexive, instantaneous duration), than AFAICS he just looses 1 FP in each second in which the NPC makes an involuntary Per roll with range penalties. It's not so much an Achilles' Heel as "Flee from anything that shows up on this Detect."

[johndallman]

Originally Posted by Mr_Sandman

Also, I'm noodling around with the consequences of treating it one way or the other, and I suppose I'm just curious about the 'original intent'.

I find effects like this reasonably persuasive that the original intent was different.

[Mr_Sandman]

Originally Posted by johndallman

It may not take any figuring out. If the NPC has Detect (Something the PC has, Reflexive, instantaneous duration), than AFAICS he just looses 1 FP in each second in which the NPC makes an involuntary Per roll with range penalties. It's not so much an Achilles' Heel as "Flee from anything that shows up on this Detect."

That's a possible interpretation, but the text from Powers for Reflexive says it can switch itself on "in the presence of something 'interesting' if a sense". Something that has already been detected a second before and accounted for might not count as 'interesting'. I was thinking more along the lines of arranging multiple attacks from the rear hex, to keep activating the detect.

[munin]

Powers mentions Detect being a transient ability: "A few transient abilities also require Concentrate maneuvers … Detect …" (p. P154)

That makes sense to me -- you activate it, it gives you information, done.

Costs Fatigue would then cost 1 FP per use, where a use is the Concentrate maneuver to get information.

Without Precise, you know the direction but not the distance which in combat is equivalent to not knowing what hex the target is in which makes targeting difficult. With Precise, you do know the hex so you can attack, or Aim then attack, or whatever.

You could use Reflexive, but Reduced Time would be sufficient -- then you can simply take a free action to detect each turn. Reflexive is for when you want the ability to work when you don't know you need it to.

If you want something you can activate for a minute, try Scanning Sense or Vibration Sense.