Clearly, thri-kreen are meant to resemble some kind of eusocial insects, most likely ants or termites; I’m not entirely sure which one. (ETA: On Reddit, ghost_warlock kindly refers me to Wikipedia, where “the very first line . . . explains that they’re ‘mantis warriors.’ I am suitably shamed over not having thought to check Wikipedia for the answer.) However, these four-armed humanoids don’t possess the kind of hive mind or hive mentality you might attribute to them, based on their appearance. They’re not telepathic, nor are they even lawfully aligned. They don’t sleep, though, and they have the ultimate poker faces, betraying nary a hint of emotion.
Being chaotic neutral rather than chaotic evil, thri-kreen largely want to be left to their own business. The Monster Manual flavor text does say they “consider all other living creatures as potential nourishment,” and in the inevitable silly twist, “they love the taste of elf flesh in particular.” (Between thri-kreen and perytons, I’m getting the impression that elves must be delicious, like truffles or something.) But this seems to me to verge on evil, so I’d say that thri-kreen don’t attack other humanoids just to eat them unless they’re experiencing some kind of shortage of other foods. That being said, having already killed a humanoid for some other reason, they probably wouldn’t have any scruples about consuming the corpse.
Thri-kreen have high Dexterity and above-average Strength and Constitution. This gives them a bit of flexibility between brute melee combat and skirmishing, perhaps with a slight bias toward the latter, since they’re fast-moving (speed 40 feet per round). They also have proficiency in Perception and Stealth, plus Chameleon Carapace, which gives them advantage when trying to Hide. All these factors point toward ambush as a favored strategy. (more…)