How can you create a combo with Doomsday, Commander's Sphere, Bolas's Citadel, Emergence Zone, Repay in Kind, Lich?
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[START OF COMBO]This combo can be formed with Doomsday, Commander's Sphere, Bolas's Citadel, Emergence Zone, Repay in Kind, Lich

Color identity: B
Mana cost: {4}{B}{B}{B}{B}{B}{B}
Steps:
  1. Cast Doomsday by paying {B}{B}{B}, searching your library and graveyard for Bolas's Citadel, Emergence Zone, Repay in Kind, Lich, and any other card, exiling all other cards from your graveyard and library, and then placing the remaining cards on top of your library in the order previously listed and losing half your life, rounded up.
  2. Activate Commander's Sphere by sacrificing it, drawing a card.
  3. Cast Bolas's Citadel by paying {3}{B}{B}{B}.
  4. Play Emergence Zone from the top of your library.
  5. Activate Emergence Zone by paying {1}, tapping, and sacrificing it.
  6. Cast Repay in Kind from the top of your library by paying seven life.
  7. Holding priority, cast Lich from the top of your library by paying 4 life.
  8. Lich entering the battlefield, causing you to lose life equal to your life total.
  9. Resolve the Repay in Kind, causing each player's life total to become equal to the lowest life total among all players.[END OF COMBO STEPS]

Result:
  - Infinite lifeloss[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Doomsday must be in your hand
  - Commander's Sphere must be on the battlefield
  - Bolas's Citadel must be in the graveyard or in the library
  - Emergence Zone must be in the graveyard or in the library
  - Repay in Kind must be in the graveyard or in the library
  - Lich must be in the graveyard or in the library
  - Your life total is at least 24.
  - You have not played land this turn.
[END OF COMBO PREREQUISITES]
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