Basically, youll always be able to play your commander assuming you have the mana available, so having a great one will make a tremendous difference in every game you play
As a play on the classic card Necropotence, Necrodominance is a black mana card that serves as a perfect example of how the color handles gaining resources and advantage: power at a cost
The object is to reduce your opponents health to zero, by breaking through their defenses one way or the other
For two mana, you get to grab a creature from the top five cards of your deck, exiling it, and letting you cast it this turn
In general you want to cut tap lands like the Thriving lands and Temples for untapped duals like shock lands, fetches, or whatever else you have available