A key card for this commander is Gray Merchant of Asphodel, which can be cast for 3 mana and 4 life thanks to Krrik, but it will return you at least 15 life
Here are the current available letter codes for the second slot: W White U Blue B Black R Red G Green Z Multicolor X Split cards (That's split cards that aren't monocolored
The tricky part about this card is that anything that would happen while taking damage still occurs, your life total just doesnt change
How youre going to use Doomsday varies with the format (Cube, Vintage, EDH), but youll usually want a card like Laboratory Maniac or Thassa's Oracle and draw spells like Gush or Gitaxian Probe
But it just wasn't quite there in The Brothers' War Limited, and that will likely be the same for EDH
It's got seven power, a super strong enters trigger, and can even be used as a removal spell if we really need it