I think the minimum needed is just this.
In the bullet list of all auto-attacks, after "Righteous Fervor (from Oathkeeper mastery), add:
- Onslaught (from Berserker mastery)
In the bulleted list under the heading “Bonus damage”, add:
- Onslaught. At 16/16 it deals 170% weapon damage, adds 101 flat cold damage and adds 1 Onslaught stack up to a max of 5 stacks, which can be increased by the Endless Rage modifier. See DeputyChuck's Ill-advised, half-baked, misinformed, and probably wrong guide to Onslaught (A very obvious WIP) for a discussion of Onslaught stacks and their power.