The Melusai are a hard hitting elite units; Blood Sisters with their Heartseeker Bows, and the Blood Stalkers who hits can turn their foes into crystal.
via the Warhammer Community
https://www.warhammer-community.com/2018/02/21/daughters-of-khaine-preview-part-3-the-melusaigw-homepage-post-3/
A shadow is falling on the Mortal Realms – the Daughters of Khaine have come. Infused with sadistic cruelty and holy purpose, these brutal zealots will soon be yours to command thanks to a new battletome, new units and of course, Morathi herself! In our latest preview, we’re looking at the shadow of the Daughters of Khaine – the serpentine Melusai.
The Daughters of Khaine were formed by Morathi from the aelven soul essence drawn out of Slaanesh when each of the Dark God’s captors took a portion to shape to their will. While, in the Age of Sigmar, many aelves are born by natural means, some of those first aelves to be formed by their gods still walk the Mortal Realms.
The Melusai are among the first such aelf-souls to be reborn – not quite reincarnations of those consumed by Slaanesh, but new beings imbued with centuries of hatred and an unquenchable lust for revenge against the servants of Slaanesh. Melusai are twisted in spirit and body, hence their strange mutations, but have powerful magical abilities, such as the Blood Sisters’ ability to transform their foes into statues of living crystal or the Blood Stalkers’ uncanny ability to strike the hearts of their foes with their arrows.
Blood Sisters are an elite, fast-moving unit, possessing both a strong normal attack profile and the ability to dole out mortal wounds with ease. Each model in a unit of Blood Sisters can make a Crystal Touch attack as well as striking with its heartshard glaive – if the former hits, it’ll deal a mortal wound to the foe. You’ll want to use these warriors to deal with your enemy’s heavily armoured units while your Sisters of Slaughter deal with the rest of their infantry.
The Blood Stalkers, on the other hand, provide an invaluable source of ranged support to the Daughters of Khaine – after all, charging the enemy head-on is one thing, but previously, the army would struggle against foes that protected their more fragile support units, like Wizards and War Machine crews, safely behind their lines. Few are safe from the Blood Stalkers, each bearing a deadly heartseeker bow. While this makes for a powerful weapon in its own right, the Heartseekers ability is where it really shines, providing you with a source of mortal wounds at range.
Between these two units, you’ll be able to diversify your Daughters of Khaine army lists and master new strategies – pick the right general and you’ll even get to use Blood Sisters as Battleline in your matched play army. They’re far from the only new servants of the Shadow Queen, however…