Mechanically, the card is super-cool
The evil Queen and her Magic Mirror, on the other hand, are a completely different story
Ob Nixilis asks you if youd like to turn your seven-drop creature into a Griselbrand trigger
Whenever you attack, for each opponent, create a 1/1 white Human creature token that's tapped and attacking that player or a planeswalker they control
However, its in Arthurs ability that he truly shines: when played, he can give a chosen character Challenger +2 and Resist +2 (that means they get +2 Strength while Challenging and a reduction of 2 damage thats being dealt to them), plus they can also challenge Ready, not Exerted, characters on the same turn too
Similarly, most of the enchantments in the deck are auras that enhance critters, like Rancor , All That Glitters , and Almost Perfect