Like most Magic: The Gathering cards, the value of Abu Ja'far depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Arabian Nights)
I prefer this in decks that care about the graveyard to make the self-mill into a card advantage engine
As for what's covered by the Early Access system, The Pokmon Center says any items (including preorders) are eligible, especially if there is a high demand for the product
It wasnt until the release of 2024s Murder at Karlov Manor set that Sorin became a dominating force
The second problem was when I printed one of the cards it printed poorly
So it's just such an immense threat, and it's colorless energy requirement is so versatile that it'll show up in a lot of decks just as long as it's in the format