From the preview:
When the village is threatened, able-bodied farmers and craftsmen of the Wyldfolk tribes form up into bands known as Bladeslingers - a tribal militia armed with the traditional Wyldfolk spear-sling. This sturdy two-handed spear has a sling attached to its back end; the leverage from the spear haft gives the stones thrown from it deadly momentum.
The missile attack of the Bladeslingers is complemented by their ability to make a long charge and engage the enemy from a distance with their spears.
Bladeslingers are highly offensive but evaporate fast in lengthy combats against heavily armored troops. The key to success with Bladeslingers is to pick your fights wisely and to gang-up on enemy models while staying out of their melee range (keeping in mind the Bladeslingers' above-average melee range of 2 inches).
Perhaps best deployed in several medium-sized units, they can serve multiple roles wearing down the enemy with sling shots before charging in for the kill. In small units they also represent an effective distraction or a sacrifice to tempt enemy charges.