You can read the wiki to learn about what they do. But basically there end up being two options:
A. Once you get 100 of them, trade them in for a 5-star trinket and vendor that for 10,000 crowns. In this way, each spark is worth 100 crowns.
B. Occasionally you may actually want a little bit more shock, fire, or freeze protection. So you might actually wear those trinkets. I never do.
It's possible that you can trade sparks for certain materials, which you can then sell to other players for more than 100 crowns per spark. I don't know about that.
Historical note: These things have not changed much since the game launched over 4 years ago. In that time, we've gotten loads of offensive trinkets and a way to make heart trinkets reliably. So the trinkets that sparks yield are much less valuable than they used to be. They need updating.
You can read the wiki to learn about what they do. But basically there end up being two options:
A. Once you get 100 of them, trade them in for a 5-star trinket and vendor that for 10,000 crowns. In this way, each spark is worth 100 crowns.
B. Occasionally you may actually want a little bit more shock, fire, or freeze protection. So you might actually wear those trinkets. I never do.
It's possible that you can trade sparks for certain materials, which you can then sell to other players for more than 100 crowns per spark. I don't know about that.
Historical note: These things have not changed much since the game launched over 4 years ago. In that time, we've gotten loads of offensive trinkets and a way to make heart trinkets reliably. So the trinkets that sparks yield are much less valuable than they used to be. They need updating.