It has a powerful ETB effect when first played, and then if your opponent can't deal with it fast, it eventually becomes a creature and gets to reuse that effect over and over as it attacks
Too expensive, not enough rate, annoying to have to sacrifice our four-drop to get a minor effect
Blue and white have many incentives to play artifacts like metalcraft and affinity, so its easy to jam a lot of artifacts
Commons/uncommons/rares together Holofoils and reverse holofoils together EX, GX, V, Vmax, and Ultra rares together All Cards over $5.00 will be batched together
After a decade out of the card game, ACE SPEC cards were reintroduced in Japanese Scarlet & Violet expansions Wild Force and Cyber Judge (released in English as Temporal Forces), which also introduced the first ACE SPEC Special Energy card, Neo Upper Energy