It is effectively card quality although in a very unusual guise
The Full Decklist As with the other Warhammer 40,000 decks, Necron Dynasties has more brand new cards than reprints
In practice, shuffling once is sufficient, but effects that care about you shuffling your library (like Psychogenic Probe, for example) will see that you've shuffled twice
A common case being on combat tricks like Ranger's Guile and Snakeskin Veil, and sometimes those big creatures that are hard to interact with are positive additions to their environments (looking at you, Carnage Tyrant)
You could also look online for trading card shows that you can go to and sell your cards in person
Its a lhurgoyf trample enabler, but it also wants you to treat them like samurai and have them attack alone