Magnus Black is a villain that appears in Bakugan Battle Planet who works for AAAnimus Inc. and is a rival to The Awesome Ones. His Guardian Bakugan is Darkus Nillious and he also owns a Fangzor and Webam.

A masked boy wielding the powerful Nillious who becomes Dan’s number one rival. Magnus has no interest in fame and keeps his identity a mystery. Despite working for AAAnimus, Magnus is a strong believer in the bushido code of the samurai— though he has clearly lost his way.

Armed with a cadre of powerful Bakugan, Magnus is the best Battler out there... Except for Dan Kouzo. Magnus takes an instant dislike to Dan because it's obvious that this boy is special and his bond with his Bakugan is noble. Magnus turns his jealousy into drive, dedicating himself to becoming the best battler possible in order to take down Dan Kouzo, and save his sister once and for all.

(Source: Bakugan Wiki)