In terms of appearance, I have a pretty good idea of how the army of monsters in my fantasy series is going to look. In terms of biology and behavioral patterns, I have been taking inspiration from other creatures other creatures that use a caste system. In all these cases, monsters with a caste system act as a virtually unstoppable force against mankind. Imagine what beasts such as this would fare against medieval armies with magic and dragons. Such a conflict would be terrifying to behold. In terms of presence, my army of monsters will have an ominous and mysterious presence as they slowly encroach on human territory. This is similar to how the White Walkers gradually made their way to the Wall in Game of Thrones, attacking and killing everything in their path. Overall, I am rather intrigued with tinkering with this concept.