Its hard to say why, precisely
Due to the wording of this ability, it's advised to use repeatable effects that are capable of milling small numbers of cards at a time in order to create a zombie horde, as milling a massive portion of one's deck at once will only result in a single zombie being created
Having ways to protect your commander that can be customized to meet your needs is just comfortable
Transforming versions of villains was a great option for rares and mythic rares, but it was important to have something to feel villainous at lower rarities
Based on Urza, High Lord Artificer , this card creates a 0/0 colorless creature that gains a +1/+1 counter for each artifact you control
This hard-to-find mythic rare has been incredibly costly, so if youre a fan of the challenge of trying to mill out multiple opponents who start the game with 99-card decks, heres hoping the cost will come down considerably once a bunch of Ravnica Remastered packs are cracked open