While there are options outside of the deck for this commander that would be smooth, within the precon there are only five cards that deal with life loss
Not only did it have the necessary tools to fight Mono-Black Aggro, but it also had evasion, disruption, and a fast clock for fighting Field of the Dead
It also inspired a fun Un-set card, Enter the Dungeon
Almost every Ragavan, Nimble Pilferer deck plays the two-mana sorcery alongside it, as the more mana you can create, the better Iteration is as it is not being forced to take lands from it/having the mana to be able to cast any card you hit makes Iteration closer to a two-mana spell that draws two of the top three cards, which is utterly broken
That archetype traditionally doesnt have a ton of card draw options, mind you, making this a bit more valuable
Four toughness