In order to go to the treasure chamber together with his friends, Yuno confronts Mars alongside Klaus, so that the injured Mimosa can heal herself. But they have a hard time harming Mars at all.
He's the Diamond Kingdom's 
secret weapon, after all.
.سلاح مملكة داياموند السّرّيّ
die Geheimwaffe des Königreichs Diamond.
l’arme secrète
du royaume de Diamond.
Lui è l'arma segreta del Regno di Diamond.
Ele é a arma secreta de Diamond.