Mineral Nexotrap

Thrown at a Mineral Nexomon, it adds 35 to your capture chance. At a Nexomon of any other element it adds 15, still more than a plain Nexotrap.

Dragons count it for half, Legendary and Ultimate Nexomon for half too, and on the Abyssal maps it counts for about a third. You throw it from the capture option, which only shows in wild battles that allow it. How the whole chance adds up is on the Nexomon page.