|Mantis Warriors (previously known as Mantis Legion)|
|Battle Cry||For The Emperor! For Redemption! For the Mantis Warriors!|
|Number||Approximately 100 remain (probably more after the Indomitus Crusade's Primaris boost in the 42nd Millenium)|
|Founding||8th Founding. Mid-34th Millennium|
|Successors of||Marauders (White Scars lineage)|
|Chapter Master||Khoisan Neotera (former)|
|Homeworld||None (previously Ootheca)|
|Strength||~100 Marines, rebuilding but still dying out|
|Specialty||Guerrilla warfare, hit-and-run, misdirection aided by divination by their Librarians, tactical applications of twinlinked multilasers|
|Colours||Emerald green, Camouflage|
The Mantis Warriors (formerly known as the Mantis Legion) are Ninjas in SPACE. They were one of the chapters guarding the Maelstrom warp Storm in Ultima Segmentum. When the Astral Claws rebelled against the Imperium of Man, which came to be known as the Badab War, the Mantis Warriors joined them because they were allied for a long time and it seemed like a good opportunity for some ass-kicking. First, they looted a Fire Hawks' ship, shattered the Marines Errant attack force, and lost when two other loyalist chapters kicked their asses.
Only 300 or so Mantis Warriors survived the fighting. They have been granted Empy's pardon (since the now-Red Corsairs were corrupted by Chaos, but no one knew about it) and sent on a 100-year penitent crusade during which they could not recruit new marines. The Space Sharks, with a silent acknowledgement from the Fire Hawks, took an entire generation of Mantis Warriors' homeworld denizens and forced them to fight to the death, taking those that survived with them to replenish their losses. The Mantis Warriors are notable for being one of the few chapters who used camo patterns on their armour - during the Tranquility campaign, their armour had yellow and black tiger stripes pattern.
But most importantly, they are White Scars successors, which implies a heavy use of bikes (even though their Forge World rules don't give much incentive for that), have subtle Henshin influences, have a specific mutation that grant them extraordinary focus and combat skills during battles, and name their companies after giant bugs that live on their homeworlds. This means that it is extremely likely that at least one of them is a grasshopper-themed biker ninja with extensive bionic enhancements. Yep, the Kamen Rider exists in 40k. And it is awesome. Uniquely, their Librarians use " Mantis Staff", double-bladed Force Staff which had a bayonet style blade.
In the "Warrior Brood" novel of Leprechaun "Multilassur" Goto, the Mantis Warriors are now seen as outcasts but aren't Chaos or Renegade marines. While they were already given the Emperor's Pardon, the Imperium, being paranoid fucks to everything that casts a shadow, still holds a strong sense of distrust among the Mantis Warriors due to their treason during the Badab War, so their only real home in the grimdarkness of space is their Battle-barge. In the aftermath of their Herodian IV defense against the splinter Tyranid Hive Fleet alongside Deathwatch they were whittled down to about 100 dudes so the Inquisition decided to let the poor guys recruit more neophytes before the grimdark galaxy (read: their own paranoia) caused the end of their Chapter. However, since Great Rift, the Warriors unable to recoup their losses are slowly being eroded.
One other interesting trait of the Mantis Warriors is a gene-seed mutation similar to but distinct from the Blood Angels' Black Rage. Through deep religious meditation and acts of penance, the Mantis Warriors can enter a state of supreme focus known as Battle Haze that gives them bullet time-style ninja reflexes. Problem is, the state is permanent and those who enter it spend the rest of their lives completely catatonic whenever they're not in combat. Those who have entered the Haze have their own special Death Company-inspired unit called the "Mantis Religiosa." No idea why most of them don’t do this and just live in stasis when not deployed. I mean, look at the Charnel Guard. There's also an Unforgiven style hunting cadre called "Praying Mantidae" that tracks down the Red Corsairs, and war veterans "Tranquility Sniper Squads".
04:00: Wake Up. The Mantis Warriors climb out of their cocoons. As soon as it hits 04:59, the Mantis Warriors race to the chapel.
05:00: Morning Prayer. The Mantis Warriors will imitate an ancient Terran insect when praying to the Emperor. Most battle brothers can barely stand due to the sheer exhaustion from running full speed to the chapel. Those who cannot stand are typically yelled at by the Chaplain.
06:00: Morning Firing Rites. The Mantis Warriors fire on targets. These targets will often be comprised primarily of Tyranids. The use of twin linked multilasers is permitted only to those who believe they can hit a fly with it. Those that do are immediately put into important command positions.
07:00: Morning battle Practice. The Mantis Warriors attack the remaining Tyranids. Using multilasers to the face is heavily encouraged.
08:00: Morning Meal. The Mantis Warriors attempt to emulate the Raven Guard and be undetectable when eating their breakfast. This usually fails, and so the chapter serfs are knocked out to hide the evidence.
10:00: Tactical Indoctrination. The Mantis Warriors gather to study hit-and-run tactics. During this time, alien Mantis are released upon Tyranid microforms, so that the battle brothers may learn better how to deal with the threat.
12:00: Afternoon Meal. The Mantis warriors will eat any Tyranids they killed in the morning. This time, they stay in visible sight and will often try to hit each other and run away with the food. The chapter requires the Tyranid be cooked using a "Mantis" pattern multilaser.
13:00: Afternoon Firing Rites. The Mantis Warriors will fire their weapons upon Tyranid cutouts. This time, the entire chapter is permitted the use of twin linked multilasers.
15:00: Afternoon Battle practice. The Mantis Warriors descend to Tyranid contested worlds to capture new targets and food for later. Killing a Carnifex with a Power Swatter earns the battle brother the title of champion of the chapter.
17:00: Mantis Religiosa Training. The Mantis Warriors select battle brothers to become Mantis Religiosa. This ceremony involves copious prayer to the Emperor, meditation, and the application of an alien Mantis to the battle brothers head. Accidentally killing a Mantis during this ceremony is considered arch heresy and the offending marine is shot with multilasers.
18:00: Evening Meal. The Mantis Warriors consume a grand meal of food that would make even solar admirals envious. Any cold meat or food is heated with a mantis pattern multilaser.
20:00: Evening Prayer. The Mantis Warriors thank the Emperor for another day of killing Tyranids, for the holy twin linked multilaser, and their first captain, Constatine Stutendious Gotoral. Any brother caught praying to be a Mantis is inducted into the list to enter the Mantis Religiosa.
21:00: Free Time. The Mantis Warriors engage in recreational activities. Studying bugs and mantis is one of the most popular activities, while others prefer observing an ancient relic called "A Bug's Life". Making fun of Tyranids is also encouraged.
23:00 Bedtime. The Mantis Warriors return to their cocoons for the evening.
Forge World has released rules for all the chapters in the Badab War. The Mantis Warriors are... a mixed bag. First, their non-bulky models gain Move Through Cover and Hammer of Wrath and if they declare a charge while in cover, they gain Furious Charge. The whole army can also re-roll Seize attempts. It's an obviously melee-focused set but prevents terminators and jump infantry (traditional marine melee) from benefiting. However, it can be fairly puissant if coupled with pistol or shotgun scouts. For elite options, there's the honour guard or a veteran/command squad in an assault transport.
Eighth edition, of course, negated the above rules. They're probably best served as Blood Angels at this point, although the Black Templar chapter tactics could work, as well, if one wanted to keep them codex-compliant.
As of 8.5, they are officially rolled into White Scars successor chapter rules.
As of 9th, you're just better off sticking with White Scars or, better yet. Pick two from the Successor Chapter rules that fit. They suggest that for the Badab War chapters that got to stay in the new Forge World compendium, anyhow.