It’s clearly designed for Death Knight (Soldier/Necro) or other characters using Aether damage. It focuses mainly on Aether damage, for which Warlords (Soldier/Oathkeeper) don’t have support. You’ll need the Necro mastery here.
Since you already started playing an Oathkeeper, I’d suggest making a Warlord out of your character. Warlords were somewhat OP at the beginning of the “Forgotten Gods” expansion. Hence they were nerfed several times… They probably aren’t “top tier” any more, but they are still very “viable”. Besides that, Warlords can always be played with physical damage without conversions or anything that would require special items. They are a very good class to gear up “step by step”.
Some months ago, I started my journey into GD with a Warlord. The character took me to (early) endgame and - what’s most important - gave me the opportunity to farm for gear for the following characters. I used malawiglenn’s “beginner spinner”. You can find it here:
Good luck on your journey into GD!