Let's revive an old tradition, and find a way to logically explain how things in the Telepath Universe work. We've explained how many attacks work, and even how the various orbs work. But I find that we are now at a conundrum. Why are spriggats weak against their opposing element?
Examples:
Why would a spriggat that breathes fire be particularly weak to cold?
Why would a spriggat that breathes ice be particularly weak to heat?
Why would a spriggat that breathes corrosive miasma be particularly weak to electromagnetic radiation?
Why would a spriggat that breathes high doses of electromagnetic radiation be particularly weak to corrosive miasma?
This is the puzzle that we need to solve!
Let's try coming up with reasonable explanations before we ask The Creator.
Well, the Red and Frost Spriggats are relatively easy. I am fairly sure each of them is accustomed to very warm or very cold habitats, respectively, and so their abilities in homeostasis are largely geared towards cooling and warming, again, respectively.
When a Red Spriggat is hit by ice or cold, it's a supreme shock to the system -- their body is very much unable to handle it. Even if they see it coming, and are ready for it, the cold can still throw them off their guard with its sheer shock value.
Same for Frost Spriggats and heat, really.
As for Golden and Dark, that's a bit harder, and I'll leave it for either someone else or for another day.
I was assuming the same about the Red and Frost Spriggats. But as you said, the Golden and Dark are a bit more of a puzzle.
Why are stone constructions weak to light?
Light attacks are combined radiation and pressure--it's the pressure part that has such a deleterious effect on stone, due to its brittle nature.
I suppose Darkness attacks are similarly actually a combination of negative emotional energy and corrosion?
If so, do you see the corrosive aspect as being a physical manifestation of the metaphorically corrosive/toxic nature of those emotions, or as a separate physical, chemical phenomenon (like an acid or a base being formed, analogous to ice shards and fireballs of a cryo- and pyrokineticist, respectively)?
[With the moisture in the air, you could form nitric acid or ammonia, which seem appropriately primordial (especially ammonia) for a form of psionically produced material, but given that much of TRPG:SoG takes place in a desert, skiakinetics might be a little touch-and-go if it were to rely on humidity.]