Its a three-mana 2/2 Vampire, which can make it good in any deck with Vampires at all, but its also one with built-in card removal
One of the difficulties in trying to make creatures have an impact on Standard is that they normally have to have an immediate effect on the game
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
After all, Sir Charles had woken me up the night before by lowering his ever-fragrant butt onto my face at three in the morning
His willingness to chant enthusiastically at top volume about anything, at any time, for any reason, is the stuff of legends
The fact that it gives the caster a ton of mana in return makes it miles better than the already pretty powerful Counterspell