The boss of chapter six. Two smaller spiders help him. Kill these two first - otherwise they will pester you with their pitiful attacks. The optimal pair for this fight is Finn and Robert. The former can attack with water and the latter is able to attack all three targets at once, which makes getting rid of the two spiders easier, while damaging the main spider. The boss and his wingmen can shorten the cooldown of their turns, lengthen yours or even paralyze your characters. During this fight, you have to keep your eye on the health of your characters - should it drop below 100 points, use healing potions.
This boss is able to attack both characters at once, but they have a chance of dodging these attacks.
Before you get to the boss itself, you have to fight three spiders in this location. All fights look the same. Three spiders attack; you should respond with regular attack - they deal similar damage to strong attacks and in addition cancel the turn cooldown of your enemies.