How artifact durendal works?

Answer 1

Artifact Durendal is an XYZ monster that requires you to overlay 2x Lv5 monsters.

It has two Quick effects, only one can be activated per turn. Both require you to detach one of the XYZ material.

The first effect is used when a monster effect is activated, or when a spell or trap card is activated. When it resolves, it replaces the effect with 'Destroy one spell or trap your opponent controls'. So say you had a monster effect that was not particularly useful, you could activate it anyway, and use Artifact Durendal to turn it into a spell/trap destroying effect. Or say the opponent activated a particularly dangerous effect, you could change that to a mere spell/trap destroying effect instead - you'd lose a spell or trap card, but avoid whatever the effect was supposed to do.

The second effect says that if any player has any cards in hand, they shuffle those cards back into the deck and draw the same number. If a player has no hand, then they do nothing, but the effect will resolve as completely as it can, shuffling the opponent's cards into their deck.