Complex sentence: Sergei Michailovich Trufanoff, a.k.a. as Iliodor, was an author, and is known primarily for his work, semi-autobiographical on himself, and biographical on Rasputin.
Split into simpler sentences: Sergei Michailovich Trufanoff, a.k.a. Iliodor, was an author. He is known primarily for his work, semi-autobiographical on himself, and biographical on Rasputin.