The cover of the first edition shows a warrior facing off a snaky monster in the mists of Atlantis.
Tools of the trade in Tobin's home office include traditional pencils, paper and a drawing board; a computer with Photoshop and other software, Wacom drawing tablet and interactive pen.
But tool skills can be learned.
Above all, imagination, drive and the ability to "put your ideas down in a medium that other people can see" are key, Wootten says. "What you can bring to a project creatively."
The career paths of both artists are not short on variety and they continue to evolve.
Art was actually not their best subject at high school. Wootten was good at science and studied zoology at university, Tobin preferred archaeology and ancient history; they both eventually did degrees in art and design.
Partway through a science honours degree Wootten baulked at the idea of becoming an academic. Taking time out, he worked as a hospital orderly for a while and "sort of got back into art" - he had always been "not bad" at drawing Dungeons and Dragons characters, and animals. The dabbling led to a three-year degree in visual arts.
In 1996 Weta Workshop ("a place I'd never heard of") snapped him up.
Friend and sculptor Jaimie Beswick, also featured in White Cloud Worlds, had rung and said, "You've got to come."
"So I sent a couple of photos to Richard [Taylor] and he said - come on up," Wootten says.
He brought his knowledge of animal anatomy and behaviour to creating dinosaurs for King Kong. He also worked on The Lord of the Rings and The Lion, the Witch and the Wardrobe.
Wootten likes creating the weird out of the real, where "normal" contrasts disturbingly with something that isn't - like the lone wolf whose backbone bristles spikes in a snarling pack. (White Cloud Worlds book one.)
Now freelance, he works for role-playing games companies around the world and enjoys doing illustrations that are the finished product. He produces about 12 illustrations on any given project, averaging one a day.
Different jobs allow him more or less creative leeway. The more prescriptive a brief and style, the more he is paid.
Wootten says concept design is not the same as illustration. Design drawings are part of a process towards a product, whether it is a suit of armour that has to fit a real person, a creature that has to look real to an audience, or a toy product associated with a movie. The final product may not resemble many of the design drawings.
"Film is really energetic and exciting, you're with a lot of amazing people on amazing projects," Wootten says.
"Creatively there's a lot of waste because you do a lot of design that's never seen on screen."
But some previously unseen design art for films is now appearing in books.
Tobin points out that because of the technology directors will often be attracted to beautifully illustrated designs - "so there is the trick that if you can combine a great illustration with a great design it's a win/win. That's why a lot of concept designs look like illustrations."
Being skilled at both design and illustration can be an advantage.
While freelancing is a challenge and requires business skills, Wootten says illustration is now a more viable career because of the internet and broadband.
"In the 1990s there was only a handful of illustrators in Wellington and they were all struggling to get enough work [locally]. You had to physically get your painting to the [client] and meet the people."
Tobin began his career at Weta Workshop in 2003. He was working at the coroners office "reviewing database entries of how people died" when he was given a two-week trial and stayed. The first Narnia film and King Kong were underway but Tobin says he was "lousy at drawing dinosaurs" so he stayed with Narnian fantasy. Drawing on his background in ancient history and archaeology, as he often does, he created concept designs for Peter and Edmund's armour and weapons and Susan's horn.
"Going from [the office] into the high-pressure environment of the design room was quite hard but you just have to hit the ground running, and Weta is supportive, people rally around you."
He says they are lucky working on a variety of films at Weta Workshop. But concept designers are cogs among many in a big process that involves a lot of working through.
"In design "you are exploring disposable ideas on paper. Peter [Jackson] will probably say 'No' nine times out of 10, until he says, 'Yes'. Then it's a matter of taking the finished design, detailing it up and getting it to a point where it can be built."
And concept designers have to be a bit of everything. "One day you're an architect designing the interior or exterior of a castle or a ship, without the project management, or making of it, the next you're a fashion, or industrial designer. It's an incredible career and also very challenging because you are expected to be all or most of these things."
Illustration out of work time and editing books is another stream to his creative flow.
