Doomsday | Commander's Sphere | Bolas's Citadel

(and two other cards)

Doomsday in hand.
Commander's Sphere on the battlefield.
All other permanents in your graveyard or in your library.
You have at least 11 life.
({3} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) available.

Cast
Doomsday by paying ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) , 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.
Activate
Commander's Sphere's first ability by tapping it, adding one mana of any color.
Activate
Commander's Sphere's second ability by sacrificing it, causing you to draw a card.
Cast
Bolas's Citadel by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Cast
Aetherflux Reservoir from your library by paying 4 life.
Cast two other cards with mana value 2 or less.
Aetherflux Reservoir triggers, gaining you 1 life for each spell you have cast this turn.
Cast
Black Sun's Zenith by paying 2 life and shuffling it into the library.
Aetherflux Reservoir triggers, gaining you 1 life for each spell you have cast this turn.
Repeat until your life total is 53 or greater.
Activate
Aetherflux Reservoir by paying 50 life, dealing 50 damages to any target.
Repeat from step 8.