Complex sentence: During Day's absence from the world of costumed crime, an as-yet-unnamed criminal acquired the Stilt-Man armor, and after upgrading its telescoping abilities, was defeated by Daredevil and Luke Cage.
Split into simpler sentences: During Day's absence from the world of costumed crime, an as-yet-unnamed criminal acquired the Stilt-Man armor. After upgrading its telescoping abilities, this Stilt-Man was defeated by Daredevil and Luke Cage.