Paladin Kran and the Staff of Illusion

In the first book of the Battle of Heartwood Series, Kran, a small boy from a small village where size and muscle are all that matter, is chosen to be a Paladin of the World Tree and is paired with the Staff of Illusion. Together he and the staff he names Oko, work to stop the warlord of the barbarian army, Secundus, from attacking his home and destroying his village and worse yet, harming his mother. But they have their work cut out for them when they realize that Kran can only make illusions as pranks. Can Oko keep Kran laughing and pranking his way to saving his village?