Irrelevant backstory: a PC in a Kingmaker campaign just purchased a magic item granting +4 to Craft (Trapmaking), which brings this PC's total skill to 25. Thus the PC can "Take 10" to succeed on a daily craft check even at DC 35. The PC is an arcane caster and wants to make Spell Traps.
How does a PC crafting Spell Traps work? The trap rules are pretty straightforward. Here is all we are told about Spell Traps.
(Note that Spell Traps are a subset of Magic Traps. Magic Traps are either "Spell Traps" or "Magic Device Traps".)
Magic Traps: Many spells can be used to create dangerous traps. Unless the spell or item description states otherwise, assume the following to be true.
* A successful Perception check (DC 25 + spell level) detects a magic trap before it goes off.
* Magic traps permit a saving throw in order to avoid the effect (DC 10 + spell level × 1.5).
* Magic traps may be disarmed by a character with the trapfinding class feature with a successful Disable Device skill check (DC 25 + spell level). Other characters have no chance to disarm a magic trap with a Disable Device check.Magic traps are further divided into spell traps and magic device traps. Magic device traps initiate spell effects when activated, just as wands, rods, rings, and other magic items do. Creating a magic device trap requires the Craft Wondrous Item feat.
Spell traps are simply spells that themselves function as traps. Creating a spell trap requires the services of a character who can cast the needed spell or spells, who is usually either the character creating the trap or an NPC spellcaster hired for that purpose.
Spell: All spell traps have this kind of trigger. The appropriate spell descriptions explain the trigger conditions for traps that contain spell triggers.
No Reset: Short of completely rebuilding the trap, there's no way to trigger it more than once. Spell traps have no reset element.
If the builder of a trap wants to be able to move past the trap after it is created or placed, it's a good idea to build in a bypass mechanism: something that temporarily disarms the trap. Bypass elements are typically used only with mechanical traps; spell traps usually have built-in allowances for the caster to bypass them.
Spell Traps: Spell traps produce the spell's effect. Like all spells, a spell trap that allows a saving throw has a save DC of 10 + spell level + caster's relevant ability modifier.
As with mechanical traps, decide what elements you want and then determine the CR of the resulting trap (see Table: CR Modifiers for Magic Traps). If a player character wants to design and construct a magic trap, he, or an ally, must have the Craft Wondrous Item feat. In addition, he must be able to cast the spell or spells that the trap requires—or he must be able to hire an NPC to cast the spells for him.
For a magic trap, only one modifier applies to the CR—either the level of the highest-level spell used in the trap, or the average damage figure, whichever is larger.For a spell trap or magic device trap, the base CR is 1.
A table shows the two modifiers. +1 per spell level is one option. +1 per 10 points average damage is the other. So the higher of those two is added to the base CR of 1 to find the total CR of a Spell Trap
A spell trap has a cost only if the builder must hire an NPC spellcaster to cast it.
Now my questions...
First, the Craft Skill DC to craft a Spell Trap is not provided!
Am I missing something?
Perhaps there is no DC because there is no cost? But that makes no sense. Every spellcaster would be making dumploads of Spell Traps!
It seems more reasonable to use the table for Mechanical Trap Crafting DCs.
By that table, most any PC with one rank per level in Craft (Trapmaking) can reliably put any spell he or she knows into a Spell Trap, even if Craft is not a class skill or Intelligence is mediocre.
Second, how long does it take to craft a Spell Trap?
With no cost, the Craft skill works in one day. Fair enough.
Third, how is the Spell Trap triggered?
Is this just what the GM and PC agree upon?
For example, a carved piece of wood made into a Black Tentacles Spell Trap would trigger the first time it touched a floor, since the spell only effects floors?
As another example, a carved piece of wood made into a Touch of Idiocy Spell Trap would trigger the first time it touched someone, since the spell has a range of touch. The trap crafter could use tongs to put it into a small bag, then try to empty the bag onto a foe.
But a carved piece of wood made into a Reduce Person Spell Trap would be impossible to carry because being within 25' or so of anyone would trigger it?
The rules said that Spell Traps were supposed to have bypass conditions, but that is never explained. A bypass condition would allow lots of spells (like Reduce Person) to be made into portable Spell Traps.
Fourth, is the cost really free?
True, there is a substantial investment to just be able to create Spell Traps: the Craft Wondrous Items feat, ranks in Craft (Trapmaking), and knowing some spells.
Moreover, many spells cannot be safely carried around in a Spell Trap because they would trigger by being in range of any creature/humanoid/etc.
Finally, a 2,500 gp Ring of Sustenance is usually needed for a PC to have time to do crafting while adventuring.
But... it appears that every day the PC can now make a one-use magic item for free with a sizeable number of spells. That seems ridiculously efficient compared to the rules for creating a magic scroll or suit of chain mail.
For example, any PC that can spontaneous cast cure spells could move his or her highest un-used healing spell for the day into a one-use item before bedtime.
As another example, there is no rule prohibiting spells with range of Personal. That rule is probably intended to exist, to prevent bypassing the prohibition with potions ("I can't make a False Life potion for the Fighter, but I can give him a False Life Spell Trap to touch!").
Your thoughts, please?
Hm. Two more thoughts...
(a) Perhaps a Spell Trap with range of "Personal" would only function if touched by the creator (or caster helping the creator). That would severely limit those.
(b) Is there a rule about how long it takes to arm a trap? It reasonably takes more than six seconds to set up and position a bear trap, even a well made modern one. I could not find anything in the Rogue or Feat rules. But that would be a sensible way to balance Spell Traps. "Sure, you can craft a Black Tentacles pebble for free -- but it is a non-combat option useful for trapping a doorway because it takes 1 minute to arm by carefully attuning the local magical energies."
You can't craft a Spell Trap. A Spell Trap simply means there are certain spells that, when cast, act as traps. There's nothing to do to create a spell trap other than cast the spell (or have someone else cast it). All the details of how that "trap" works are in the text of whatever spell that may be.
A Magical Device trap, as it says, requires the appropriate Craft item feat.
You can't craft a Spell Trap. A Spell Trap simply means there are certain spells that, when cast, act as traps. There's nothing to do to create a spell trap other than cast the spell (or have someone else cast it). All the details of how that "trap" works are in the text of whatever spell that may be.
A Magical Device trap, as it says, requires the appropriate Craft item feat.
Ah. I was very confused.