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
What a Cartoon! ended on June 1, 2008. In 2007, reruns of "What a Cartoon!" played briefly on Cartoon Network's retro animation sister channel, Boomerang. "What A Cartoon!" is the 1st short cartoon incubator created by Fred Seibert. Starting with WAC! and continuing throughout his cartoon career, his Frederator Studios has persisted in the tradition of surfacing new talent, characters, and series with several cartoon shorts "incubators," including (as of 2016): "What A Cartoon!" (Cartoon Network, 1995), Nickelodeon/Nicktoons' own "Oh Yeah! Cartoons" (1998), "Nicktoons Film Festival" (2004), "Random! Cartoons" (2008), "The Meth Minute 39" (Channel Frederator, 2008), "The Cartoonstitute" (Cartoon Network, 2009/unfinished), "Too