Like most Magic: The Gathering cards, the value of Nazgl depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (The Lord of the Rings: Tales of Middle-earth)
Even if you are not building around speed the efficiency of this card is still too good to turn down
When you do, cast it for its madness cost or put it into your graveyard.) Flavor Text The question strained his sanity
I think its one of the single best cards in any kind of black mirror, and I think it is perhaps the most important card you can put in your sideboard against the Supreme Verdict decks
This is an immensely powerful effect, especially in a black control deck (be it Commander or otherwise) that cares about dealing with any threat your opponent might have in their hand, on the board, in the graveyard anywhere