This is the first enemy with a ranged attack that the player will encounter in the game. The Blue X Walker can be dangerous this early in the game. It has the potential speed and strength to kill weak characters, especially if a group of Blue X Walkers is protected by some Red Smiley Walkers.
One way to beat them is to use the Bait strategy, so ranged characters can attack without being damaged. Another way to beat them is to outrange them with some ranged characters, as most ranged classes are able to outrange this enemy, anyway. The Dodge strategy can also be used as their ranged attack is slow and can be dodged easily. Melees are also recommended to defeat them so that they draw attention to it, while ranged characters can pound on it with little trouble.
They are an excellent resource for early game Magicians due to their Blue Stone and Explosion drops. Six of them can be found in the stage's ninth screen.