3.5 Mechanical Traps: Clarification on Creation CR

[Adept_Scholar]

I have a few questions concerning the creation of mechanical traps after reviewing table 3-13 on page 74 in the 3.5 D.M. Guide:

1. Alchemical device---Does this mainly reference the items: acid (flask), tanglefoot bag, thunderstone, & tindertwig on page 128 in the 3.5 P.H.? If so, how would I go about determining the increase of CR for a given trap of this type-simply go through all the spells to see which ones most closely mimic the items' effects?

2. Liquid---I am assuming this only applies to a water-type trap that fills a room (as such an amount of poison would be unlikely)? I imagine this could also be for other substances, such as sand?

3. Multiple Target---This is +1 CR if affects 2+ targets? Why is it +0 to CR if it never misses?

4. Onset Delay---This refers to how long it takes for the trap to activate when triggered?

[Adept_Scholar]

Also, I am a bit confused about the cost of a mechanical trap...On page 75 of the 3.5 D.M. Guide under "Mechanical Trap Cost", it states the minimum cost for a mechanical trap is CRx100gp, so if the trap is a CR 1, then this would mean a mechanical trap costs a minimum of 100gp; however, the paragraph before it states that the base cost of a mechanical trap is 1,000gp. Clarification? :smallconfused:

[Adept_Scholar]

To update, after looking over the section again, the answers to my questions can be found (mostly) on page 70 in the 3.5 D.M. Guide. However, I am still curious as to the spell that causes deafness and would replicate a thunderstone's effects...:smallconfused:

[Fizban]

The default would be Blindness/Deafness, though it's only single target at 2nd level. However, deafness and thunderstones by extension are overrated. The main effects of being deafened are a -4 on initiative checks and a 20% spell failure, both of which are outclassed by 1st level spells found elsewhere (not being able to hear means little when you can technically see in all directions). I wouldn't value deafness as more than a 1st level spell.