You can copy simple yet powerful abilities, like planeswalker abilities and anything coming off historically powerful cards like Aetherflux Reservoir and Portal to Phyrexia
One memorable collection I purchased a few years ago had a bunch of so-so rares from Invasion through Mirrodin
It doesn't fully get rid of them, only shuffles them into the deck but this temporary removal can be enough to hinder the opponent
Most Commander decks are loaded with low-quality filler cards to keep costs down, which comes at the expense of power, performance, and ultimately fun
This appears to have been revealed during the Black Lotus VIP event along with Narset
You can find 1 mythic rare borderless planeswalker, 1 mythic rare borderless adventurer card, and 5 borderless rare or 4 mythic rare cards from the set in Draft Boosters, Set Boosters, and Collector Boosters