Complex sentence: He began his career with Valiant Comics, at their height, as Production Manager, where he also earned writing credits on the "ARMORINES-Yearbook", "MAGNUS 2001", and an unpublished issue of "Archer & Armstrong".
Split into simpler sentences: He began his career with Valiant Comics, at their height, as Production Manager. His writing credits include the "ARMORINES-Yearbook", "MAGNUS 2001", and an unpublished "Archer & Armstrong".