That's a reference to the One Ring from The Lord of the Rings , and it's not a particularly strong mechanic
A reasonable middle ground is using Requiem Monolith in combination with larger damage effects to draw a decent amount of cards
As for the Pac-Man Select store, it only involves merchandise
For one black mana and a few sacrificed Squirrels, you can give any creature +X/-X, either pumping up one of your creatures a bit or taking down your opponents commander at the cost of a few creatures.
Enabling coven isnt the easiest since it requires a constant board state thats always vulnerable to removal, and Sigarda can easily die before you see the first card
Duskmourn: House Of Horror's Endless Punishment Commander deck, however, looks beyond merely doing damage on your turn and instead tries to deal damage on every other player's turn too