Perhaps its the power dynamic created by untapped Islands, the idea that you suddenly need to wait for your opponents permission on every attempted play
I think either Weatherlight Compleated or The Indomitable is my favorite existing option, but both of them shine a spotlight on archetypes in their colors (or lack thereof) that had few compelling options
The issue was that they didn't like it mixed into the set
While on paper, this battle looks decent, I don't foresee this getting a ton of play
Now, you're probably wondering: if the rares and mythics are worthless and the commons and uncommons are worthless, where does the value come from in an Un-set
Sauron is expensive for a commander, and without the land ramp afforded by green, you'll need to run a lot to mana rocks to play him early enough to matter