Ellyrian Reaver

In the time of Caledor, all Ulthuan was in turmoil and the armies of Malekith roamed freely, destroying and slaying at will. With his armies already stretched to the limit, the Phoenix King called for brave young horsemen to ride the troubled land. Many youths answered his call, eager to prove their worth, but the greatest in number by far came from Ellyrion, a land renowned for its fine horses and skilled riders. Throughout the long and bitter war and into the dark days of the Sundering, these valiant riders served Caledor well. In small groups, they travelled quickly and secretly across the land, taking messages and soliciting support from amongst the Elven realms, ambushing patrols and intercepting raiders. Caledor named the swift Elven horsemen his Reaver Knights, and they have been known by that title ever since.

These Ellyrian Reavers were skilled at living deep inside enemy territory, finding their sustenance in the wilds and launching ambush after ambush upon the foe. Their tactics were aggressive to the point of recklessness, striking hard and fast against the more ponderous enemy formations before vanishing into the wilderness. Soon, Malekith's dread armies became wary of leaving their fortified encampments, except in large numbers. Yet the Reavers' worth lay not only in direct battle. When not fighting, they spread the word of Caledor's struggle, helped loyal Elves to escape the Witch King's clutches and fostered rebellion within his ranks. At that time, not all who followed Malekith were fully commited to his tainted cause, and some could be drawn back to the light with a well-spoken word of deed.

To this day, Ellyrian Reavers still form a deadly part of Ulthuan's armies. They rove the wild lands of Ellyrion, slaying the monstrous beasts that leave the borders of the Annulii and seek to rampage through the Inner Kingdoms. Many a Cockatrice or Chimera has been laid low by the well-placed arrows or spear thrusts of the noble youths, and many more Dark Elves had had their cruel raids cut short. Indeed, such pride do the Ellyrian Reavers take in their kills that many of the young nobles keep a tally of slain foes. When the sun sets and the fighting ceases, he whose spear has felled the greatest number of enemies is granted the honour of carrying the regiment's standard into the next battle. However, he who slays the mightiest opponent receives Kurnous' favour; when next he rides to war he will do so as one of Kurnous' Harbingers, blessed with peerless aim by the wild god of the hunt.

Source

 * Warhammer Armies: High Elves (8th Edition) -- p. 44-45