The most versatile of Scorched Earths creatures. A Mantis can hold the roles of multiple different creatures depending on the tools or weapons it has equipped. Picks and Hatchets make them ultimate harvesters, Pikes and Swords can turn them into deadly combat mounts and Clubs can allow them to quickly down creatures for taming, they have no need for Sickles since they can harvest fiber by default. However you'll need to level it's stats depending on the role you plan to assign it to. For example, if you want too make a Mantis a harvester weight and Melee are what you'll want to go for, if you want it to be a expert at combat health and Melee with some stamina in case things go wrong and you have to flee are the way to go since there pounce attack is enough to quickly cover ground and escape a aggressor, and KO'ers really need nothing more then health in case the target is something strong that fights back and some Melee to increase the amount of torpor inflicted by the clubs
There is a great video on how to kill death worms very early game on YouTube by a guy named fresonis which involves using oil jars and flaming arrows to kill it and catch it on fire while it moves underground. This strategy is great for early game players with limited resources as it only takes around 4-5 oil jars and flame arrows to kill a level one death worm. This is a great way to farm horns for mantis taming.
If you are taming these for their Eggs, make sure to place them in an area that's "Unknown" (changed to "Wilderness" in recent patch). It'll quadruple your Egg harvest. Just leave render range for 5-10 minuted, come back and collect your eggs. They can also be egg-boosted by a Oviraptor now so make sure one is in range.