Complex sentence: The symbol of the change was the new cover feature, "Warriors of the World", replacing "The Swots and Blots" who, drawn by Mike Lacey, had occupied the cover during the final part of the Odhams years.
Split into simpler sentences: The symbol of the change was the new cover feature, "Warriors of the World". This now replaced "The Swots and Blots", who, drawn by Mike Lacey, had occupied the cover during the final part of the Odhams years.