At the beginning of each upkeep, Tombostone Stairwell's first ability triggers, causing each player to create a 2/2 Zombie creature token for each creature card in their graveyard.
At the beginning of each end step,
Tombstone Stairwell's second ability triggers, destroying all tokens created by it.
When the token(s) die,
Nadier's Nightblade triggers that many times, causing each opponent to lose that much life and you to gain that much life.
Repeat during each turn.
Results
Near-infinite lifeloss.
Near-infinite creature ETB.
Near-infinite creature LTB.
Near-infinite death triggers.
Near-infinite lifegain.
Near-infinite lifegain triggers.
Metadata
Bracket tag
RuthlessBracket 4+
For competitive decks at brackets 4+
1
2
3
4
5
1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.