We refer to these as "mana sinks." In our Eldrazi disruptive aggro deck, we have a few cards that act as mana sinks
Valgavoth, Terror Eater Atraxa, Grand Unifier has a new challenger at the top of the reanimator food chain
There are some nice synergies that the Knight type can grant you, The Circle of Loyalty etc., so this could see Commander play for that reason
Two card boxes The Coldsnap Player's Guide, with images of every card in the set and background information on the set available nowhere else One Pro Player Card Six color dividers to keep your cards separated in the card boxes A Coldsnap Spindown life counter Jeff Grubb's classic Ice Age novel The Gathering Dark, one of the most popular Magic novels ever.
Recursion, Tutors and More In my opinion the above categories are the most important to be thinking about while building a deck, but there's three more types of cards I wanted to discuss