Meaning of ご帰還あそばれなされた


Full sentence: 「俺様がご帰還あそばれなされたぞ！」 I think this sentence means something alike
to: "I have returned!"

My main problem with this sentence is the usage of あそばれなされた. From my
understanding, this is the verb 遊ぶ, and looks like it's conjugated to it's
causative-passive form on the past tense? This conjugation looks really weird,
I have checked Jisho and I'm not sure which conjugation it seems to be, but
regardless of this I'm not sure what the verb 遊ぶ could be doing in this
sentence together with 帰還.

