I heard i can zerk immunes down then stick on the boss as frenzy
That is correct, I am a Berserk barb fan, not too much Frenzy, however, when doing Ubers, you concentrate on the Uber Boss using Life Tap wand and deal with the immunes later. All melee characters doing Ubers will have a Life Tap wand.
Basics are to cast life tap on the Uber Boss and tele stomp him ignoring the others... as a Frenzy barb, you could also Howl the lesser monsters away.
Again a frenzy barb can do it, thus gear is needed, and I would not use Oath... but then you have to build around what you need:
For Ubers: Melee
Life Tap, IAS bp, life leech, frw, cbf, max or stacked res, open wounds would be good, crushing blow and tele... FRW would be good, and of course decent damage and a way to recast Life Tap while in combat.
Above is just my generalization of what is needed.
The low budget Black smiter works, CB is optimized as well.
So I am guessing you will need an Enigma of some kind, the gloves that has a % ctc Life Tap (also has Life Leech I believe), Highlords or Maras? Highlords would be optimum for the IAS ... Griefpb would be my choice based on easy to get IAS BP.
Not sure on Frenzy, but I am sure you can check it out, or someone more experienced can help you.
Now I have forgotten everything that I use on my Hammerdin Smite build, it only uses 1 base point Smite (I add to this when other skills are optimized).
On Switch for Smite:
Griefpb + Exile.
Enigma
Shako or Ral'd Andys... sounds strange right ... well Andy's for IAS / Life Leech and Strength, as for Shako, just for MF with Hammerdin.
War Trav boots, mf and some added damage.
Gloves with % ctc Life Tap
2x Raven frost
Maras
Spirit ST
Hotos or Spirit Sword for FCR & Res.
Inventory, basics and res to max or overcap.
Yeah, basic crap, but I use this on LoD SP8 with Plugy, all self found gear.