The Big Rubble is a ruin infused with ancient giant magic, at least in places. In addition, many cults and potent creatures call the area home. With all of this magic hanging around, it makes sense that it would have some unique fauna. Well, here is one more.

Sort of. 

The Giant Praying Mantis has been a creature in Glorantha for a long time, At least since Trollpak, so over 30 years anyhow. The product of the worship of Gorakiki, the troll deity of vermin - the Giant Praying Mantis has been a beast of burden and a war animal for trolls for centuries.

In the Big Rubble, conditions are different than they are in many troll areas. There is little in the way of vegetation, much more ruin, and broken buildings, fragmented wooden beams, jagged stone, etc. Since the Mantis relies on stealth fro its hunting method, it stands to reason that a Rubble-bred mantis would start to look less like a standard praying mantis, and more, well,  ruiny.

Hence the Ruin Mantis.

Beginning with normal Praying Mantids, and selectively breeding them for greyish chitin and off fibrous projections on the arms, thorax and abdomen, the cult of Gorakiki has, over the last century created a mantis that is exceptionally good at camoflage in ruin such as make up sizable portions of the Big Rubble (to such an extent that Argan Argar trolls now joke that it should be renamed the Bug Rubble). Of course, trolls being the rather disorganized, somewhat lacadazical creatures that they are, many of the Ruin Mantids escaped captivity and have adaped easily to the wild. 

Ruin Mantids are generally ambush predators like most other mantids, striking from concealment with both massive talons, gripping their victim, then bringing it to the mandibles for quick and messy dissection. Because of their preferred environment, Ruin Mantids have become quite a threat to explorers and treasure hunters in the Big Rubble, who often are particularly interested in venturing into prime Ruin Mantid habitat. Currently, several portions fo the Troll Strongland, as wellas nearer sections of Huntland and Temple HIll, have Ruin Mantid infestations to one degree or another. Gimpy's and other "adventurer" bars probably have Work for Hire signs offering bounty on Ruin Mantis antenna. Even Lunar Patrols are worried.

Ruin Mantids were first bred as trollish “home defense” and eggs were often scattered about the periphery of troll settlements blessed by the presence of Gorakiki Mantis cultists. However, the giant creatures also make excellent bugs of burden and war-mounts. So it should come as no surprise that several Karrg's Sons have bene seen riding Ruin Mantids of late.