Welcome to the Doomsday Wiki!
The Doomsday Wiki is intended to be the most complete and up to date work on how to cast the card named Doomsday in the Legacy format of Magic: the Gathering.
There is actually much more to how to play the deck, but understanding how to cast the namesake card of the deck is a pretty big piece of the puzzle. This is specifically not a primer as you often see for other decks in Legacy, because primers generally become outdated rather quickly and are more about card choices, decklists, sideboard tables, and so on. The Doomsday Wiki is there to help people to really understand how the deck works and can win in various scenarios.
We have three main variants represented on here that you can access resources for from the left-hand sidebar.
Doomsday refers to the primary deck variant that is having previously unprecedented success since the printing of Thassa's Oracle. Legacy Doomsday uses countermagic like Force of Will and discard like Thoughtseize to play a controlling game before ending the game. On occasion and unless it leads to an entirely new Doomsday engine, a new spoiler will shake the meta up but it will usually be discussed alongside the main variant.
DDFT (Doomsday Fetchland Tendrils) is the closest to historical lists. Although it adopts the current usage of Thassa's Oracle, these decks tend to also have access to secondary Storm plans using cards like Burning Wish, Echo of Eons and Tendrils of Agony. They also prefer proactive protection like discard over being able to run reactive permission.
Entombsday is a Tin Fins variant with a maindeck plan focusing on reanimating Griselbrand using tools such as Shallow Grave or Goryo's Vengeance to then have it attack alongside Emrakul, the Aeons Torn or looping the deck to generate infinite mana and cast your entire library an infinite number of times. The key point to focus on is that it runs a dedicated transformational sideboard into a variant of Doomsday.
If you are new to the archetype then check out the FAQs Appendix for any initial queries you might have. Peruse the Wiki, read some of the articles and come visit us in the Discord.