This boss is essentially a stronger Grey Triangle Walker. It shoots 3 bullets in a high arch, which pierces characters and each exploding into 9 fire attacks on contact with the terrain. Due to its full-screen range, and the somewhat random trajectory of two of its bullets, its attack can be incredibly dangerous, as the fire residue can deal incredible damage to groups of characters. The best strategy is to have a single melee character distract the boss, while the other characters defeat the White Triangle Stickmen that also inhabit the screen. Also, once they're finished, they'll be out of range for the most part of the boss's attack. Be sure the distracting character avoids the bullets, because the flames can deal a dangerous amount of damage in a short time span. Ice, Poison, and Thunder type weapons are best against this boss. If the character distracting the boss is a melee, a Critical's Card and/or Berserk Card can help become the boss much easier to beat once its Stickmen allies are gone. However, in the case of the Berserk Card, dodging must be more precise.
This is the second enemy in the game who can drop at least two different levels of the same compo item, the first being the Ice Castle Boss.