If youre wanting to take longer turns and do more math in your game you should absolutely have those last two cards on the battlefield at the same time ( )
Dragon Frontiers' Charizard Gold Star was one of the first times it was seen in its iconic black shiny coloring, which alone is usually enough to make a card shoot up in value
Search your library for a creature card with mana value equal to 1 plus the sacrificed creatures mana value, put that card onto the battlefield with an additional +1/+1 counter on it, then shuffle
His two triggers generate both mana and cards, potentially in large quantities, and the deckbuilding and gameplay hoops he asks us to jump through are manageable
Both trigger when one of the own creatures dies
If you have two other Nazgls in play and play a third, each gets three +1/+1 counters: one from the two already on the battlefield and the third from the third entering