So I’ve had quite a lot of fun and success with a build that goes all in with Captain Crimson in quite a novel way by running the Obsidian Ring of the Zodiac and Elusive Ring in my ring slots (not in the cube), freeing up my Kanai’s Cube slots for anything I like.
Due to the obscene level of cooldown reduction (40% and resource cost reduction (80%) that I have even with quite basic gear, coupled with Obsidian Ring of the Zodiac, I basically have Vault for 1 discipline and Shadow Power for 3 discipline, which I get to keep up permanently. I also get to use Vault as if it were teleport, and can add the Danetta benefits to it too.
I also don’t need Dawn for permanent Vengeance, since my Vengeance cooldown basically snaps back to ready almost instantly. This allows me to keep Kanai’s Cube slots for more useful things like Stone Gauntlets or Squirt’s Necklace.
I have preparation with Focused Mind (Gain 45 Discipline over 15 seconds instead of restoring it immediately.), which thanks to Obsidian Ring of the Zodiac I also get to have up permanently. Basically, my discipline regenerates faster than I can spend it even if I just faceroll all abilities over and over.
Basically, I have managed to achieve a build with infinite resources that also gets obscene amounts of damage reduction and extra damage from it, while simultaneously keeping 2 cube slots open and flexible.
This is probably a well-known meta thing, since Diablo 3 is over a decade old, but just wanted to share in case someone found it inspiring. From looking around, I did get the impression that the Obsidian Ring of the Zodiac was more common as a cube slot than as a worn physical item.