Shaper
"This pigeon is so raw it could still fly."
- – Gordon Ramsay
Shapers are the spiritual leaders of the Turkeybois and are, for all intents and purposes, in charged on what is on the menu. This is because of the Kroot's biological and evolutionary quirk, in which they gain DNA of each prey animal they eat, which than transfers onto the new generation. Nomming the wrong things may lead an entire kindred into an evolutionary dead-end, or even worse.
Overview
Shapers have two jobs. The first is the aforementioned culinary inspection. Like a hyper-evolved version of Spore, if the Shaper wants his kindred to learn the art of the swole, he would direct to target and chow down on specifically Orks and Ogryns. If the Shaper wants his bois to be a bunch of prancy little knife ears, he would target Eldar. If he wants to show extreme devotion to a certain corpse-ridden skeleton with the most FABULOUS of hair, he will go for Imperials. Whatever is the case, the evolutionary path of the Shaper's kindred is his responsibility alone.
The second job is to act as Sergeants in a battlefield. A large kindred is typically run by a Master Shaper, while a group consisting of multiple kindreds may be headed by a Shaper Council of three to five Kroot, who act as overseers to the other shapers, and ensure that shapers do not lead their warriors down a dangerous evolutionary path. Occasionally a Shaper Chief may rise to power in times of emergency and unite hundreds of kindreds as a single army.
They also have shamanistic powers, like Disney's Pocahontas, but somehow less historically egregious and insulting. This is due to them being the focus of Kroot ancestor worship of their Kindred, practising rituals that seem to fill them supernatural powers, usually involving a sonorous chant and access to the powders, rocks and bones kept within the Shaper’s fetish pouch.
Among these powers are Ancestral Blessing, calling the warrior spirits of his ancestors to aid the Shaper and his allies, Blood of the Stalker, daubing himself and his allies skin with the blood of a local predator and with a prayer to gain the favour of the ancestors and grant helping them with hunts, and Prophetic Dream, visions from their ancestors that grant him foreknowledge of the future that is often difficult to understand, a vision which may relate to something in the next week or even years.
Crunch
In 8th Edition, the Kroot Shaper is a support hero for the Kroot, buffing leadership of Kroot units within 6" to his ld7, and in the improbable occasion he kills with his knife, they also don't have to test morale. He is more usefully also re-rolling wound rolls of 1 and a Pack Alpha Stratagem improving charge rolls. He makes Hounds and Krootox Riders Dangerous while keeping pace. You always want to upgrade his rifle to Pulse, since both are free.