The magician is an unlocked character at the start of the game. He sends balls of blue electricity that become violet at level 3. When he attacks, he retreats, so you better avoid attacking with the hole behind him.
Do not use at level 1, because, most of the time at this level, the balls do not appear. In fact, it is better to use it only at level 3. A push on the attack button throws 3 balls at level 3. As always, it takes 2 shots to kill a small opponent and 4 for a big one, as for any character sending projectiles (he, the archer and the knight).