Mox Diamonds updated rules text makes it so that the card cant enter the battlefield at all unless you discard a land card, so you cant tap it without having discarded a land card because it just wouldn't enter the battlefield
That said, Staff of Compleation has a real price associated with its modes
You can buy individual packs, each with 15 cards, or a booster box containing 12 packs
Ideally, what you want are a cheap dork with a lot of disadvantages with a fat power to grab a lot and a decent toughness to pump him up
Since the story of Kamigawa Neon Dynasty involves this transformation by Tezzeret and Jin-Gitaxias, this makes sense
To round it out, weve got Angus Mackenzie (LP) with timeless Commander charm, and Mana Drain (LP) as one of the most elegant pieces of vintage interaction ever printed