Save DCs and attack bonuses for magic traps

[ericthecleric]

Does anyone have a page reference for determining the above, or know the answer to the above? ie. how to determine attack bonuses for magic traps, and how to determine save DCs?

On save DCs, I would have thought that they're determined in the usual method for magic items, ie. 10 + (1.5 x spell level); but, [spoiler] Man Forever in Dungeon 137 has a few slay living traps with a DC of 27 (normally it would be 17 or something like that).

With the attack bonuses, is it trap creator's BAB + Dex (for a ray) or what?

[ZeroCharisma]

The page in the SRD is vague on the formula, if any. I believe you have complete control over setting the DC for a trap, but it is clear that a trap with a higher than average attack or DC becomes a higher CR trap.

I would advocate using a similar system to designing monsters and encounters. Barring any special circumstances, the Save DC should come in at about 10 higher than average party level, and an attack should be {average party level x 1.5 +3 or 4}. Deviation from that would increase or decrease the CR accordingly. This definitely falls under the purview of opinion as I have no factual basis to back it up with.

[Saern]

Not a particularly useful post, most likely, but I just felt like chiming in and saying that I've always felt that the CR for many magic traps is far too high. This is particularly true in the case of the classic fire trap spell. The CR 5 version of the trap listed in the DMG is cast by a 7th level character and does a whopping 1d4+7 damage- hardly a threat to most characters at that level. This is, at most, a minor annoyance, yet it is the same CR as a fireball trap set by an 8th level caster, which will deal 8d6 damage to a much larger number of creatures. An elite, world-renowed archmage of 20th level can deal a maximum of 24 points of damage with this bad-boy. Oh, wait! Meta-magic. Adding Maximize and Empower Spell increases that to a screaming 26 damage! As opposed to a fireball trap cast by a mere 10th level mage, which deals a measly 10d6 damage (average 35, maxmum 60).

Is fire trap useful? Yes, it's dirt cheap compared to other magical traps. Does it come close to the CR the DMG lists for it? Nope!

Just thought I'd mention that.

[ericthecleric]

But, Saern, that world renowned archmage sweated hours learning that spell…

Seriously, your post was very amusing (intentionally, I hope!). I suppose it wouldn’t be so quite so funny (for the PCs) if the fire trap protected a container with, say, 200+ gallons of kerosene, and the floor of the chamber was filled to a depth of 6 inches of water.
Fire trap is a 4th-level spell for wizards, and 2nd for druids, so maybe the CR for them should be 3, as the CRs seem to be spell level +1.

Maybe that archmage would prefer, say, eight 20th-level disintegrate spells (automatic reset) in one room. Better yet, make that eight maximised 20th-level disintegrate spells. (Oh, and one fire trap as well.)

ZeroCharisma, thanks for the helpful advice. It’s a shame there’s nothing more concrete in print. Song and Silence wasn’t that much help, either.

[Adam Daigle]

ericthecleric wrote:

Does anyone have a page reference for determining the above, or know the answer to the above? ie. how to determine attack bonuses for magic traps, and how to determine save DCs?

On save DCs, I would have thought that they're determined in the usual method for magic items, ie. 10 + (1.5 x spell level); but, [spoiler] Man Forever in Dungeon 137 has a few slay living traps with a DC of 27 (normally it would be 17 or something like that).

With the attack bonuses, is it trap creator's BAB + Dex (for a ray) or what?

Once again, this is not the answer you are looking for, but I'm not sure where to look to find the "why" to the DC's for traps aside from the fact that they are indeed - traps, thus a surprise hazard of adventuring. That's not a great answer.

One thing I have done in my games is make the DC to resist the effect easier if the trap was detected. It's still hard for a rogue or scout to find a magical trap (25+spell level), so it's a minor boon, and I only apply it to reflex saves in the spirit of bracing for the effect.

[Moff Rimmer]

ericthecleric wrote:

Does anyone have a page reference for determining the above, or know the answer to the above? ie. how to determine attack bonuses for magic traps, and how to determine save DCs?

Here is some extracurricular reading regarding the above. While there is very little about the specifics on coming up with attack bonuses for magic traps, the Save DCs are (for the most part) pretty straight-forward (10 + spell level) but they can be improved.

Dungeon Master's Guide -- Pages 67-75
Dungeon Master's Guide II -- Pages 40-47

For some examples of a variety of traps and different attacks types and bonuses and CR ratings, look at the above references as well as --

Book of Challenges (the whole book is basically traps and related obstacles)
Draconomicon -- pages 84-86
Dragons of Faerun -- pages 101-103

Take a really good look at the rules for traps in the DMG and then, instead of creating a new trap, consider modifying an existing trap to be in line with the party.

I hope that this helps.

[ericthecleric]

Thanks for the tips, Moff.
While I don't have Dragons of Faerun (and have no intention of getting it), I do have the other books, so I'll have a good look at the references and see if they help at all. If they don't, then ZeroCharisma's post seems about right.

[Moff Rimmer]

ericthecleric wrote:

Thanks for the tips, Moff.

While I don't have Dragons of Faerun (and have no intention of getting it), I do have the other books, so I'll have a good look at the references and see if they help at all. If they don't, then ZeroCharisma's post seems about right.

Not a problem. I agree that ZeroCharisma seems pretty close (if not right on).

If you can get a chance to borrow Dragons of Faerun (either from a friend, the library, etc.) do so and take a look at it. There is some good generic information in there -- but if you are not running Faerun or a whole lot of dragons, I agree that you shouldn't buy it.