By Alan McCoy from Dungeons & Dragons: Fundamentals
How to build challenging encounters against
a Thri-Kreen
Note: This has been prepared utilizing only the 5E Core Rules. The Thri-Kreen can be found in the Monster Manual page 288. The Thri-Kreen was originally created for the DARK SUN setting during the second edition of the game, where they were allowed as a player character race. The entry in the Monster Manual is woefully inadequate to cover the lore of the race.
Note: The Dark Sun setting was a post-apocalyptic setting where magic is failing, and other powers had begun to emerge. This creature is not a good fit for all Dungeons and Dragons worlds and is best used very sparingly, perhaps to provide for a unique foe for your players to encounter.
Dark Sun was a setting that allowed Psionic abilities, something that mainstream D&D does not. Because the 5E MM provides a variant form of the Psionic Thri-Kreen, I will be proposing some NON RAW changes and adaptations that allow you to keep the feel of the creature, without requiring you to include Psionics in your game.
Racial Description and Lore
Often called mantis warriors these creatures are intelligent humanoids with insect like features. They prefer deserts and savannas where they maintain a nomadic lifestyle as hunters and traders.
Thri-Kreen resemble a giant bipedal praying mantis, they have six limbs, two legs and four arms. They have a sandy yellow exoskeleton. Their facial features are striking, with two compound eyes, two antennae and an insect like jaw structure. Thri-Kreen use harnesses, belts and other arrangements for holding equipment and carrying supplies but have not been observed to wear clothing or armor.
Thri-Kreen can naturally camouflage themselves by varying the color make up of their carapace making them very difficult to spot, there are limits to this ability however, which is why they prefer the deserts and the savannah.
Thri-Kreen are nomadic, and permanent settlements are not known, they are instead organized in groups called packs who maintain control over their territory. Thri-Kreen normally maintain friendly relations with the packs that border their territory and will join with and assist one another against especially dangerous foes.
To a Thri-Kreen, the Pack is everything, they gain their identify from their pack and are fanatically loyal to other members of their Pack.It is believed that the Thri-Kreen are telepathic within their own pack, and to a lesser extent, other Thri-Kreen. This manifests as a Thri-Kreen language is a mixture of clicks and snaps of their mandibles, with antennae motion employed to display emotion.
While almost total nonsense to even a talented linguist observer, the Thri-Kreen communicate quite well with it. Some Thri-Kreen have learned to speak the Common tongue, though to human ears it sounds strangely metallic and almost machine-like. It is certain that the language has no emotional component. When speaking to non Thri-Kreen, the language is often supplemented by the addition of “Picture Talk” essentially drawing pictures in the sand or dirt, or by creating small models with twigs and grasses.
Thri-Kreen physiology is very different than that of humanity. They are capable of consuming very large amounts of food when it is available and going for long periods of time between meals when it is not. They do not sleep, they rest by placing their bodies in a semi-automatic mode, alert enough to handle light tasks yet still allowing for the physical benefit of sleep enjoyed by other species; this is probably inefficient and only partially effective, as Thri-Kreen lifespan is under thirty-five years.
Thri-Kreen are egg-layers, laying a clutch of eggs that will mature to hatching in roughly ninety days, Young Thri-Kreen mature quickly, and apparently depends on the needs of the Pack. Maturity can take a long as three years but has been observed to happen in less than a year. Gender in a Thri-Kreen difficult to establish, and it may be that they are asexual.
The Thri-Kreen race is one of many that can produce exceptional individuals that can learn a character class. They favor Druid, Monk and Ranger. Their versions of these classes share abilities but have very little in common with the version known by humanoids.
The Thri-Kreen, being six limbed creatures have developed weaponry that is specifically suited to their physiology. The Gythka – a two handed and very whippy staff that qualifies as a finesse weapon and the Chatkchas — triangular throwing weapons.
Additionally, the Thri-Kreen are known to carry long cords that they can cast out and easily recover, essentially these are deployable caltrops that can be used to create difficult terrain for an opponent.
Step 1) Let’s Review what we know about the Thri-Kreen
Thri-Kreen are fast, with a land speed of 40 feet per round.
Thri-Kreen have high dexterity, above average strength, constitution and wisdom, below average intelligence and low charisma.
Thri-Kreen have proficiency in the skills of Perception (+3), Stealth (+4) and Survival (+3).Thri-Kreen have a Poisonous Bite, failure to save by more than 5 will paralyze the target.
Thri-Kreen have a Chameleon Carapace that gives them Advantage on Stealth checks made to hide.
Thri-Kreen can make standing leaps of 30 feet forward and up to 15 feet up without a running start.
NOT RAW: Thri-Kreen have EXPERTISE in the Stealth Skill (+8) This has been included to substitute for the Psionic variant abilities of Blur and Invisibility.
NOT RAW: Thri-Kreen can cast the Cantrips: Mage Hand and Shillelagh at will. This has been included to substitute for the Psionic variant abilities of Mage Hand and Magic Weapon.
NOT RAW: The Gythka is considered a quarterstaff with the finesse property for the purposes of the game. This makes the weapon eligible for use with the Shillelagh spell.
Step 2) Determine the probable Strategy
Thri-Kreen tend to be of the live and let live mentality, unless their space is invaded, or they need food. As they are desert creatures, they are unlikely to interact with others often.
When they are met in conflict, they Thri-Kreen will do their very best to kill an enemy quickly, they are very good at picking targets due to their high wisdom, using their innate telepathic communication within their pack, they instantly aware of anything observed by another of the pack.
Thri-Kreen are limited in intelligence, but what they do learn they have learned well and have passed down, layer to egg for generations. Simple yes, effective and efficient, also yes.
Note: The tactics below assume that you have adopted the weapons (step 1) and the SPIT attack (Step 4).
Step 3) Determine Tactics
When possible, the Thri-Kreen will attack at night (Darkvision).
The Thri-Kreen know their territory well and will pick a place that provides difficult terrain to their opponents, preferably near a dune or other source of cover.
The Thri-Kreen will attack from stealth and camouflage as a group, they will each SPIT their poison on a target, with smaller targets receiving more poison SPIT if the numbers allow it. Thri-Kreen have learned that big hulking brutes are resistant to poison, but the little guys rarely are.
After their initial spit volley, the Thri-Kreen will leap away, requiring any that chase them to charge into concealed caltrops and difficult terrain.
Meanwhile, the Thri-Kreen will use their superior speed (80-foot dash + 30 foot leap each round) to move around to the other side of the battlefield. Archers and spell-casters are their primary target, though anyone paralyzed will also be attacked (automatic advantage and automatic critical hit).
Should any enemy decide to cast spells or use ranged weaponry from inside the Caltrop and Difficult terrain area, the Thri-Kreen will use their Chatkcha to attack them. They will leap over the area if needed to negate cover or concealment.
Step 4) DM Tips and Observations
I debated about the inclusion of the Psionic abilities of the variant included in the MM, vs the number of DMs that are violently opposed to the inclusion of anything Psionic in their games.
I believe that I have found a suitable compromise.
The DC for the Bite Poison is too low, I suggest a DC 13. Additionally, since the bite would be a rarely if ever used attack, I suggest you allow them to SPIT their POISON to Range of up to 15 feet, instead of one of their weapon attacks. Recharge roughly once every third round, takes time to work up a mouthful.
For Clarity, when Shillelagh has been cast:
Gythka: Melee Weapon attack, +5 to hit, reach 5 ft., one target, HIT: 7 (d8+3)
SPIT: RANGED WEAPON ATTACK, +4 to hit, range: 15/30 feet, one target: Constitution Save DC 13, or poisoned condition applied. DC 8 failure = Paralyzed condition applies. Recharge 5-6.