you may look at the top card of their library any time, you may play the top card of their library, and you may spend mana as though it were mana of any color to cast spells this way. We already wrote about this floating eyeball in-depth, but the long and short of it is that you can always choose the best player for whatever you need, and thats the kind of flexibility you really want in any deck, let alone in your commander
For example, [c]Yisan, the Wanderer Bard[/c] has the unique ability to search your library for specific creatures and put them directly onto the battlefield
Once hes summoned, you get to amass a five-strong Orc army, and mill five cards to the graveyard, then choose one creature card from that lot to play immediately on the battlefield, with no need to pay the Land cost
Facilier, Agent Provocateur, this deck will almost certainly run out of cards faster
Also, thanks for reading