Barbar simply cannot compete in Ladder Season Hardcore 9. Currently Barbar would be required to complete a Greater Rift Tier 55 in less than 5 minutes to place on the Hardcore Seasonal Ladder. Unfortunately, even with an Ancient Immortal King's Boulder Breaker, this does not seem possible for an Immortal King's / Wastes Grandeur.
It took a great deal of ingenuity to construct Unity + Pledge jewelry, reducing damage to 25%. Coupled with gear of the Wastes, Barbar takes 12.5% damage while Whirlwinding with a 50% chance of Dodge, thanks to Warcry.
Barbar has the standard Armor of a Barb, and wears 5 Flawless Royal Diamonds in vestments. With the Relentless Talent, Barbar takes only 7.5% damage below 35% Health while moving and Whirlwinding. Unfortunately, Barbar was nearly killed yesterday in a Tier 52 Greater Rift by the Rift Guardian: an Infernal Maiden.
Activating Nerves of Steal to prevent fatal damage, Damage Taken was reduced to 0.375% for 5 seconds as Barbar Whirlwind'd away from the Infernal Maiden.
I am including a Youtube video of Barbar defeating a Tier 50 Greater Rift to show what Immortal King's / Wastes (Grandeur) is capable of.
GR50
Using Fury of the Ancients, Barbar generates Fury to power Rend and Whirlwind. His damage multipliers are:
x5 Call of the Ancients + Wrath of the Berserker (Immortal King's)
x1.5 Wrath of the Berserker
x6 Rend (Wastes)
x3 Rend (Wastes)
x2 Rend (Lamentation)
x~1.5 Taeguk
Barbar is also capable of Increasing Damage output x2 by Whirlwinding into a Wall and invoking the 100% damage bonus of Traveler's Pledge. We see this happen against the Rift Guardian.
Boss Fight
Farewell, Barbar.