A lot of players have differing opinions on Nazgl being viable in competitive play
(2024-09-20) If your opponent discards a card while you control Leyline of the Void, abilities that check whether a card is discarded (such as Hollow One, or a madness ability of the discarded card) still work, even though that card never reaches that player's graveyard
That price range, dependent on the number of decks demanding the card, seems to be the default setting for serialized cards that share art/frame with another card in the set
It can be played on turn 1 and that extra damage can really add up if your opponent refuses to deal with it
If for some reason you tried to generate other mana outside your color identity (like if, for example, you were playing Rakdos and gained control of someones Noble Hierarch), it produced colorless instead