Stingers are massive monsters that are very dangerous because they all have high Defense and have nasty attacks. Ultimately these are only encountered near the end of the game and ultimately are not seen again, replaced by the mighty GOLEMs.
These massive, skeletal monsters are first encountered when one attacks Aya in the Shelter. The first time they are fought after Aya returns to Dryfield. It drops Bowman's Card which is needed as Kyle doesn't give her an analogous one. They have a lot of HP and have nasty spells. As one of the few enemies that have healing abilities, the other being Glutton. They are frequently encountered in pairs.
This is an absolutely towering Stinger and is being controlled by Eve. It features several dangerous attacks but is easily staggered but the battle also features two Derangement Speakers. This is a fairly long battle so it is important to keep track of supplies.