Rythven-Fang

You do not have enough basics to warrant cabal stronghold. Best case scenario: Assuming you get 4 basic swamps + stronghold in a row, you break even. Maybe you get it late game for a tiny boost but it is negligible. You can get more value out of another utility land or a basic swamp.

Cloud Key/Semblance Anvil = Ramp

Mystic Forge = Helps more than 1/4th of your deck easily.

Ugin, the Ineffable - Helpful to get rid of rest in peace/other artifact hate. He is a bit pricey for CMC but worth potentially worth considering.

Mystic forge + artifact cost reducer (like above cards) + sensei's top = draw your entire deck

Forsaken Monument + basalt =

Rings of Brighthearth + basalt + 2 mana = = + Sensei's Divining Top = Draw your entire deck

Metalworker + voltaic key + rings =

Everflowing Chalice + voltaic + rings =

Profet93

Like some of these a lot, kind of took out some of the more dead "combos" that were filler.

Also Cabal Stronghold was always kind of meh to me, so making me go back and look at it made me look at my mana base all around and change it up. It's probably better now.

Glad I could be of assistance. Your commander costs 6 and is expensive to recast, even with coffers + artifact ramp. If you don't mind losing a draw, Volrath's Stronghold can be a backup plan (and slightly helpful against grave hate) for those late games where he inevitably costs too much.

Loving the fetchland synergy with rings. Not to mention with urborg out, u can keep them "as swamps" and use them for top deck manipulation (with top).