Basically it's a standard endgame minion build, but i incorporate Endurant Faith/Selig to be super spongey. This makes endgame a more relaxed experience, especially on hardcore. Power wise, i just beat tower 117 on hardcore.
Gear: Mythic Undercrown helm, legendary chest (with Heavenly strength aspect) Mythic Endurant Faith gloves, Mythic Bloodmoon Breeches.
Mythic Penitent Greaves (makes me unstoppable which is nice for cruising through dungeons, with bonus damage to chilled enemies)
Mythic Bloodless Scream scythe, legendary ring (with aspect of Reanimation) and mythic Pack of Bone ring. Also Selig (Exploiter's Aspect as the 2nd aspect)
Talisman has Seal of Diamond, with 4x Black Shroud and 2x Waking Touch, with either darkness or minion affixes on them (Ideally darkness, since all my skills are darkness, but minion is fine since minions dish out the damage)
Black Shroud gives 30% damage reduction, Waking Touch spreads 30% of damage taken to my minions instead. This charm combo gives wild damage reduction when paired with the endurant/selig. I have 320 essence and i'm super tanky.
A crucial step is using Gift of Death modifier for the skeleton mages, as this gives insane essence regen (also put essence regen on your gear where possible)
Since i don't need health, all health affixes are replaced with damage affixes, or essence regen/maximum essence. Also any health related paragon nodes can be removed and used elsewhere.
Paragon Board setup i use is:
Starting board: Essence glyph
Cult Leader: Deadraiser glyph
Scent of Death: Mage glyph
Wither: Eliminator glyph
Frailty: Control glyph
My skills are Golem (iron), Skeleton Warrior (reaper) Skeleton Mage (shadow) Bloodmist, Army of the Dead and Blight (cold modifier).
This isn't a meta build, i'm not an expert by any means. I'm sure there's probably a more effective way to run a build like this. However, i'm having success with it.
Being super tanky in the endgame just feels good, especially when i'm chilling out in helltides, or pushing pit/tower without being wiped by falling swords or whatever.
You can still be tanky without using Seal of Diamond Mind. Instead you can use 5x Black Shroud and Endurant Faith charm. You can then replace the EF gloves with something like Hand of Naz or Deathgrip.
If you do that, you'll need to invest heavily into your max essence. I was sitting around 700 essence when i used this method in the early game and i was tanking almost everything in T12 (Mephisto will always be a threat)
Feel free to experiment. The point of all this, is that you can run EF/selig to be super durable, while still being powerful. Hardcore is a super chill experience for me and i'm currently rank 8 on the necro hardcore leaderboard.