FromTheShire: This is mostly worth highlighting for how good it can be in non-Commander formats, although if you're running a infect/poison EDH deck you're absolutely including it as well
The above MTG cards are estimated to be the most valuable overall, but there are plenty of others worth at least a couple hundred dollarsenough to be worth covering, one way or another
Take Ugin, the Ineffable as an example: Colorless spells you cast cost less to cast. As long as Ugin is on the battlefield, your colorless spells will be two mana cheaper
ability allows his player a form of recursion by returning an action card from the discard pile whenever he challenges another character
Here are the 8 best card draws in white that you should seriously consider for any deck that is solely white or has a strong focus on it
High variance cards are typically poor design, cards like Ankh of Mishra for example