This is the [Knell Prime] build I use. The [Convulsion] mod is at rank 4 to fit in the build with only 3 forma. Any arcane can be used, based on preference, but I use Cascadia Empowered because, through tests, I found out that I get more DPS with Cascadia Empowered(rank 0) than Secondary Merciless(rank 4). You need a primer to put on enemies corrosive(for Cascadia Empowered) and other elements(for [Galvanized Shot])