ThunderCats (comics) entered the Book of Omens to begin his training and claim his rightful place as Lord of the ThunderCats, but Mumm-Ra uses a powerful spell to keep Lion-O trapped in the book for several years in real time, not "Book" time, and seizes control of Thundera afterwards. In the follow-up mini-series, "The Return" (written by Gilmore and illustrated by Benes, Pimental and Lea), published in 2003, Lion-O returned to Thundera to find it enslaved to Mumm-Ra. Several of the ThunderCats are scattered. Panthro, who was left in charge while Lion-O was away, was forced into slave labor. Tygra and Cheetara
Cartoon Network the checkerboard motif retained and the "C" and "N" being the centerpiece) and a new slogan, "This is Cartoon Network!" The bumpers introduced as part of the rebrand featured 2D cartoon characters from its shows interacting in a CGI city composed of sets from their shows. These bumpers lasted from 2004 to 2007. By now, nearly all of Cartoon Network's classic programming had been relocated to its sister network Boomerang to make way for new programming. The city era returned in the "OK K.O.! Let's Be Heroes" episode and Cartoon Network special "Crossover Nexus". 2005 saw the debuts of four