Smallpox is much the same, for half the cost of Death Cloud you can play it with X fixed at one
Board control: Black and white are both wrath colors, and there are numerous potent 1-for-1 removal spells in the color combo
Their spoiler for the day is Cryptbreaker, a 1/1 black Zombie that enter the battlefield for one black mana
This approach suits Commander best, where singleton formats reduce consistency concerns and longer games give you time to fix mana
Urzas Cave Chief: I love lands that sacrifice themselves to do things, especially when they enter the battlefield untapped
I don't believe it saw much, if any, Constructed play at the time (I may be wrong on this, but can't seem to find anything from researching online), but the card was considered quite powerful stat-wise and featured some keywords not commonly found on Green cards