Assassin Oney is a foe in Digistruct peak Challenge DLC
Oney is a Nomad by enemy type. This means he is powerful but slow moving. Keep some cover between you and him as much as possible. While he has a shield, he will not usually bring it out. He is packing a shotgun and a lot of grenades
Southpaw Power and Steam He some reinforcement and can lob grenades at you. The reinforcements, next to him, are trivial and can be taken out without much effort. If you are the optional objective of killing him with a Sniper Rifle, you will find this is a lot easier to manage.
Digistruct Peak You need to be careful as he will bullrush you on the occasion. Still, with all the cover, it is not too hard to avoid the worst of his attacks.
Fire and Headshots.