Help me make a magical trap

[Cevah]

Reading a post, I got the idea of carrying around a resetting magical trap.
This trap would trigger on Detect Evil, and I want an effect that either only harms evil critters, or buffs me and/or my allies.

I want this to also fly below "cheese" so that my GM would approve it. [Wishful thinking, perhaps.] So nothing too abusive.
Bonus points if the effect is not noticeable when in a crowd.

So the question are:
1) What do I place the trap on?
2) What effect do I want?

So looking at the rules, I see:

Table: Cost Modifiers for Magic Device Traps wrote:

Feature .. Cost Modifier

Alarm spell used in trigger .. —
One-Shot Trap
Each spell used .. +50 gp × caster level × spell level
Material components .. +Material component costs
Automatic Reset Trap
Each spell used .. +500 gp × caster level × spell level
Material components .. +Material component costs × 100

Also, elsewhere on the page is:

Trigger wrote:

Proximity: This trigger activates the trap when a creature approaches within a certain distance of it. A proximity trigger differs from a location trigger in that the creature need not be standing in a particular square. Creatures that are flying can spring a trap with a proximity trigger but not one with a location trigger. Mechanical proximity triggers are extremely sensitive to the slightest change in the air. This makes them useful only in places such as crypts, where the air is unusually still.

The proximity trigger used most often for magic device traps is the alarm spell. Unlike when the spell is cast, an alarm spell used as a trigger can have an area that’s no larger than the area the trap is meant to protect.

Some magic device traps have special proximity triggers that activate only when certain kinds of creatures approach. For example, a detect good spell can serve as a proximity trigger on an evil altar, springing the attached trap only when someone of good alignment gets close enough to it.

So I have to add the cost for Detect Evil. :-(

Still, it is cheap enough (=500 gp), and it gets me a better activation strategy.

Then there is this:

Effect wrote:

Magic Device Traps: These traps produce the effects of any spells included in their construction, as described in the appropriate entries. If the spell in a magic device trap allows a saving throw, its save DC is (10 + spell level) × 1.5. Some spells make attack rolls instead.

This makes for low saves unless I go high cost.

• 0th: DC 10 for 250 gp in 0.5 days
  
• 1st: DC 11 for 500 gp in 1 days
  
• 2nd: DC 13 for 3000 gp in 6 days
  
• 3rd: DC 14 for 7500 gp in 15 days
  
• 4th: DC 16 for 14000 gp in 28 days
  
• 5th: DC 17 for 22500 gp in 45 days
  
• 6th: DC 19 for 33000 gp in 66 days
  
• 7th: DC 20 for 45500 gp in 91 days
  
• 8th: DC 22 for 60000 gp in 120 days
  
• 9th: DC 23 for 76500 gp in 153 days

/cevah

[Cevah]

Looking for other threads, I came across the spell Improve Trap:

Quote:

When this spell is cast upon a trap, it improves one specific element of the trap chosen at the time of casting. The caster can improve the trap in any of the following ways (each one raises the trap’s CR by +1).

* Increase DC of the Perception check required to locate the trap by +5.
* Increase DC of the Disable Device check required to disarm trap by +5.
* Increase the trap’s attack bonus or saving throw by +2.
To cast this on a trap, you must know that the trap exists and its precise location. A trap can only have one improvement from this spell at a time. A second casting changes the improvement on the trap, but does not add another improvement.

I like. I will probably go for +2 DC. Having it cast only costs 80 gp from an inquisitor or a ranger, or 150 from a druid, wizard, or witch.

/cevah

[Ryze Kuja]

Cevah's Ring of Evilbane:

This ring acts like a Ring of Counterspells insofar as that it stores a spell, except this ring activates the stored spell only whenever the wearer is affected by a Detect Evil spell.

Furthermore, the target of the stored spell must exclaim "Damn you Cevah!" or "Curses! I've been Cevah'ed!" or take 1d6+lvl nerd point damage.

[Pizza Lord]

When you say that you want it triggered on detect evil, do you mean you want the trap to 'go off' when someone directs a detect evil spell into the area that that trap is in or did you mean that you are using detect evil as the proximity trigger (similar to using alarm, see invisibility, etc. which affects the trap's awareness) so that it triggers when an evil creature passes over/into its trigger area?

[Val'bryn2]

I'd be extraordinarily careful to only use buffing spells if it's set to a Detect Evil trigger. If it's an offensive spell, you'll find yourself before a magistrate for an unlawful attack on a citizen.

[Cevah]

Pizza Lord wrote:

When you say that you want it triggered on detect evil, do you mean you want the trap to 'go off' when someone directs a detect evil spell into the area that that trap is in or did you mean that you are using detect evil as the proximity trigger (similar to using alarm, see invisibility, etc. which affects the trap's awareness) so that it triggers when an evil creature passes over/into its trigger area?

It uses Detect Evil for the proximity trigger rather than alarm, so only the presence of evil will activate the trap.

Val'bryn2 wrote:

I'd be extraordinarily careful to only use buffing spells if it's set to a Detect Evil trigger. If it's an offensive spell, you'll find yourself before a magistrate for an unlawful attack on a citizen.

This is why I was offering bonus points. :-)

I don't want to hurt them so much as debuff them. A simple Bane spell would work, but the save is way to easy at 11. Even at 13 [with Improove Trap] is still quite easy. Prayer with a DC of 14 (16) is much better, but 7500 instead of 500.

/cevah

[Pizza Lord]

The key is to make it mostly trap and less magic item. The fact that you want it to be mobile skirts the line, so I think at the least, it should require being put in place and probably taking an amount of time to set up, activate/prepare, or warm/charge up. In the interest of 'flying below cheese' and making it more palatable to a GM, the one minute setup/charging time should prevent it from being used in combat (unless set up beforehand).

1. Cevah's Radiant Curtain:

——————————————————————————————————————
Cevah's Radiant Curtain (CR 3)
Type magic; Perception 27; Disable Device 27;
Effects
Trigger touch (detect evil); reset automatic, 1 minute
Effect spell effect (burst of radiance, CL 3), 3d4 damage, no save, plus blinded 1d4 rounds, DC 13 Reflex partial (dazzled 1d4 rounds).
Description
This bundle of beaded cords can be hung across a door or archway like a beaded curtain. It requires one minute to become active or recharge once placed, drawing power from its surroundings. When an evil creature touches the beaded curtain, it triggers a burst of radiance. This occurs even if they use a reach weapon or manipulate it via spells like unseen servant or telekinesis, though this might put them out of range of the effects. Environmental effects, like fireball or gust of wind that aren't under direct control of an evil creature can damage or move the curtain without triggering it unless the spells have the evil descriptor.

Price 3,500 gp (350 gp for one use trap); Cost 1,750 gp.
Automatic reset (burst of radiance)— 3,000 gp.
Trigger touch (detect evil)— 500 gp.

——————————————————————————————————————

The beaded curtain only triggers when an evil creature touches it, though it can potentially blind anyone within 10 feet when that happens (so don't stand that close). The 3d4 damage is only to evil creatures and not affected by a save. It can be bumped to 5d4 by raising the CL, which will increase cost to 5,010 gp and the Challenge Rating to CR 4.

You could also remove the detect evil spell from the touch trigger, thus saving 500 gp, though that would mean that it would trigger when anyone touches it (after one minute), including you, potentially blinding you. It would only hurt evil creatures, and you can always close your eyes when taking it down to avoid the blinding burst. It's just an option.

2. Cevah's Holy Javelin Tapestry:

——————————————————————————————————————
Cevah's Holy Javelin Tapestry (CR 3)
Type magic; Perception DC 28; Disable Device DC 28;
Effects
Trigger visual; Reset automatic, once per round for 10 rounds then recharges for one minute.
Effect spell effect (holy javelin, CL 5), Atk +5 ranged touch <—— no idea what this should be, but this feels right, 1d6 damage + impaled for 2 rounds (1d6 additional damage at start of target's turn and –2 penalty to attack and skill checks while impaled).
Description
This tapestry depicts an archer, javelineer, or other marksman. The trap becomes active one minute after being hung on a wall or other surface. An evil creature entering its line of sight (60 feet, darkvision) is attacked by a holy javelin. The tapestry fires once per round, targeting the closest evil creature (except those with total cover). The tapestry (hardness 0, 8 hp) takes no damage from bludgeoning attacks and half damage from piercing attacks (in addition to half damage from ranged attacks). If moved from its space (not just bumped or disturbed) or the surface it's on is destroyed, the trap deactivates. <—— This is to prevent you from carrying it around with you, firing at enemies.

Price 25,000 gp; Cost 12,500 gp.
Automatic reset (holy javelin— 7,500 gp.
Trigger line of sight (detect evil)— 500 gp.
(arcane eye)— 14,000 gp.
(darkvision)— 3,000 gp.
——————————————————————————————————————

Note that you could save 17,000 gp by (Price 8,000 gp; Cost 4,000 gp) leaving out the arcane eye and darkvision components and just use the integral alarm proximity trigger. That would limit your range to 20 feet around the trap rather than 60 feet (the limit of detect evil and darkvision). It would become a proximity trap instead of visual (and wouldn't be fooled by darkness, just would be much shorter range).

You could also make this as a crystal ball or globe so you don't have to place it on a wall; thus letting it guard an intersection rather than firing down a corridor. The crystal might have a bit more hardness and more hit points than the tapestry, so it comes down to style.

[Cevah]

Any other suggestions?

I would love some more ideas.

/cevah