This is a storm combo, which means it relies on casting multiple spells on the same turn. To cast spells, we need mana and cards. The mana will be provided by a mix of Nyxbloom Ancient, Paradox Engine and mana rocks, such as Mox Amber, Cultivator's Caravan and The Great Henge, which will untap everytime we cast a spell, providing more and more mana. The cards will be tutored by Razaketh, the Foulblooded, for which we need sacrifice fodder. The main win-condition is Pestilent Cauldron, which will also untap with every spell we cast, so we can use its milling ability multiple times. The lifegain it requires will be provided by The Great Henge and/or Weather the Storm. Tendrils of Agony can be a simpler, and faster, win-condition.

The key to the combo is casting Old Stickfingers for X=3. This way, all of the deck's three creatures will be tutored into the graveyard. The next step is reanimating Young Necromancer, leaving one black mana still up. Young Necromancer will reanimate Razaketh, the Foulblooded. The black mana will serve to cast Feign Death or Malakir Rebirth on the necromancer, so she can also bring Nyxbloom Ancient from the graveyard after Razaketh sacrifices her to fetch the first mana rock, usually Mox Amber. In case we don't have Feign Death or Malakir Rebirth in our hand, we'll have to fetch it by sacrificing Old Stickfingers or a creature other than the necromancer. We also have to be aware of having extra cards in the graveyard to exile for Young Necromancer before reanimating the creatures we need - in some cases, we need to leave Old Stickfingers in the graveyard instead of putting it back in the command zone.

With Nyxbloom Ancient on the battlefield, every mana rock we fetch with Razaketh will generate the extra mana we need to either cast more mana rocks or to finally cast Paradox Engine. We have to be mindful of casting the engine only if we have enough floating mana left to cast a spell in our hand and enough sacrifice fodder to tutor more spells with Razaketh - that's how the combo goes off. The steps required between reanimating Nyxbloom Ancient and casting Pestilent Cauldron, our win-condition, will vary depending on the resources we have available. However, there are some key cards that necessarily have to be cast during these steps: mana generators, which will be either free or net-positive-mana with Nyxbloom Ancient on the battlefield; creature token generators, such as Chatterstorm, which will provide sacrifice fodder for Razaketh, the Foulblooded; and Paradox Engine. Other cards that most likely will need to be cast are: Mox Amber, as it generates the most free mana with Nyxbloom Ancient; Cultivator's Caravan, since it is free with Nyxbloom Ancient and can be crewed to be sacrificed for Razaketh after generating mana; Harrow, as it can be cast with mana generated by Cultivator's Caravan and will generate 6 extra black and green mana for the following spells; The Great Henge, since its lifegain effect, coupled with Paradox Engine, negates the life loss caused by Razaketh's ability; Diregraf Rebirth, since it counts as two cards and gives us sacrifice fodder before we can tutor Chatterstorm; and Weather the Storm, as it gains us enough life to tutor more cards safely and accelerates the milling effect of Pestilent Cauldron.