Despite the five mana cost, its ability is somewhat balanced as it gets two additional lands into play, one into hand
First, youll passively lock your opponents from drawing many cards, so youre getting the upper hand in cards
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
If you are the controller of two triggers that happen at the same time, you will get to choose the order in which they get put on the stack
Emrakul, the Aeons Torn joins Griselbrand to win the match
My verdict: A solid large-capacity pick if you want something nicer than cardboard but more living-room-friendly than a hard plastic bin