Complex sentence: The Epic Level Handbook is a rulebook by Wizards of the Coast containing rules for Dungeons & Dragons 3rd edition characters to attain levels above 20, the limit in the core rulebooks.
Split into simpler sentences: The Epic Level Handbook is a rulebook by Wizards of the Coast for 3rd edition "Dungeons & Dragons". This books contained rules for Dungeons & Dragons 3rd edition characters to attain levels above 20, the limit in the core rulebooks.