Complex sentence: Another Marvel character named Destiny fought the Sub-Mariner in the 1960s; this Destiny (real name Paul Destine) was a pawn of Set who was instrumental in causing the Sub-Mariner's temporary amnesia prior to the Silver Age of Comic Books.
Split into simpler sentences: Another Marvel character named Destiny (real name: Paul Destine) fought the Sub-Mariner in the 1960s. This Destiny was a pawn of Set who was instrumental in causing the Sub-Mariner's temporary amnesia prior to the Silver Age of Comic Books.