The fact that it hits all nonland permanents makes this very potent
Im not a believer in proliferate as a reasonable way to build around energy, so Im very skeptical even of the best proliferate cards, including Atraxa, Praetors' Voice, even though Atraxa seems to have been the most popular energy commander until recently
Atsu, Ghost of Yotei Revealed today by IGN, Atsu, Ghost of Yotei appears to be the bonus card for the Ghost of Tsushima Secret Lair
Obviously, take this all with a grain of salt, but the subreddit posts claims and information have proven 100% accurate so far
Other early scarcities: Chaos Orb is another consistent high-value card from MTG's early years
Space-Time Smackdown offers only two viable tools: Rocky Helmet and Giant Cape, with the latter being the more competitive option