First, he talks about how to get ideas.As examples for getting ideas by combining elements he uses “Girls&Panzer”(Tanks+Club activities), “KanColle”(Pretty girls+morphing into battleships) and “Restaurant to Another World”(Food+fantasy).
Then he goes on to explain to keep the advantages and disadvantages of your genre in mind, using isekai as example.
In regards to Berserk’s Guts, Griffith is a character who draws out impatience, fighting spirit and loneliness, Puck is “relaxation, laughter and a "seriousness crusher”“, the current Casca is "a character who draws out feelings of guilt, uneasiness and pity”.
By arranging the characters with the intention to pull a certain something about Guts to the surface, he becomes a multifaceted protagonist.
He finishes with stating to keep a balance between using established molds and coming up with original stuff, as original doesn’t necessary mean good.