Like most Pokmon cards, the value of Aegislash 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 (Battle Styles)
In 40K, the Necrons are very difficult to keep down because theyre basically able to repair themselves and keep fighting
They should have no bends, creases, scratches, marks, white edges, folds, etc
The set does feature some new releases, mostly in the form of Mega Evolutions
Since you won't find the Alternate Art Secret Blaziken VMAX in a Prize Pack, the art used for the Ultra Rare version is considered the best
Items that are graded by a 3rd party grading service or have conditions ascribed by the sellers are not graded by auctioneer and are only mere opinions