Cube: Bastion is the best pick if properly invested. As a last resort and if not invested, you can run Assault cube.
OL Gear: Like most DPS units, Elemental DMG and ATK take priority. After that, max ammo capacity and hit rate are great additions.
Strong water DPS for bosses and single taget damage. Needs high investment with hit rate and elemental lines plus skill investment in order to shine.