Does Tryptophan Signet stack?

If multiple people run tryptophan signet will it stack on a mob? Also how do I know what skills, signets and the like do stack? There is nothing on most wiki pages.

You can't find that stuff because things like that never, ever stacks. Whenever you use a signet, hex, enchantment, stance, shout or whatever kind of skill on any target that already has that effect, it will just refresh itself, as if it were only just applied to the target.

Ahh that sucks. I was mainly aware of hexes and such, just wondered if certain things did, as this skill would be even more fantastic if it did Thank you

Not necessarily true, first thing that comes to mind is Seed of Life.

There's a few exceptions ofcourse but I didn't want to trouble the OP with this. Other skills that don't work this way are Wastrel's Worry and Wastrel's Demise. Ik pretty sure there are a few more. If that's the case, it's usually mentioned on wiki, if it doesn't say anything, it works as how I explained in my earlier post.

There are a couple of limitations associated with TS.
Firstly, there is a limitation on the maximum % slower any combination of skills can have - 50%. That is, if you were to hit a foe with 2 different spells that cause a 33% reduction in speed, they would only total up to 50%. (The exception would be if you had 1 skill that caused a greater than 50% reduction - for example Iron Mist)
Secondly, when you cast two instances of the same skill on a foe, they (usually) don't "stack" - instead they overlap. For example, if only one person casts TS on a foe at a level of 20 secs duration and -40% speed reduction, the foe will move 40% slower for 20 seconds. If, however, say 10 seconds into the first cast, a second player casts TS with a duration of 16 secs and a reduction of -30%, then the first one will continue at -40% for 10 seconds (it's 20 secs runs out) and then the speed reduction will change to -30% for the 6 secs remaining in the second cast.