How can you create a combo with Doomsday, Commander's Sphere, Bolas's Citadel, Aetherflux Reservoir, Black Sun's Zenith?
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[START OF COMBO]This combo can be formed with Doomsday, Commander's Sphere, Bolas's Citadel, Aetherflux Reservoir, Black Sun's Zenith

Color identity: B
Mana cost: {3}{B}{B}{B}{B}{B}{B} 
Steps:
  1. Cast Doomsday by paying {B}{B}{B}, searching your library and graveyard for Bolas's Citadel, Aetherflux Reservoir, two other cards with mana value 2 or less, and Black Sun's Zenith, 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's first ability by tapping it, adding one mana of any color.
  3. Activate Commander's Sphere's second ability by sacrificing it, causing you to draw a card.
  4. Cast Bolas's Citadel by paying {3}{B}{B}{B}.
  5. Cast Aetherflux Reservoir from your library by paying 4 life.
  6. Cast two other cards with mana value 2 or less.
  7. Aetherflux Reservoir triggers, gaining you 1 life for each spell you have cast this turn.
  8. Cast Black Sun's Zenith by paying 2 life and shuffling it into the library.
  9. Aetherflux Reservoir triggers, gaining you 1 life for each spell you have cast this turn.
  10. Repeat until your life total is 53 or greater.
  11. Activate Aetherflux Reservoir by paying 50 life, dealing 50 damages to any target.
  12. Repeat from step 8.[END OF COMBO STEPS]

Result:
  - Infinite damage
  - Infinite lifegain
  - Infinite lifegain triggers
  - Infinite storm count[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
  - Aetherflux Reservoir must be in the graveyard or in the library
  - Black Sun's Zenith must be in the graveyard or in the library
  - You have at least 11 life.
[END OF COMBO PREREQUISITES]
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