Have the catalyst add the new kinetic perk, kinetic tremors. Bastion is a primary slot, kinetic fusion rifle. No element. So it would make sense and I think it would pair well with the weapon and maybe even make it meta. Because of the unique way Bastion fires(3 round burst), it usually can take down any major or elite in one burst, depending on the difficulty of the activity. But this catalyst would give it that extra punch against bosses, and even help clear out a few adds. Similar to how exotics like cloudstrike and Quicksilver Storm work.