"I have come to dance the dance of death." The tag line for the harlequin from DOW.
Fast skimmers. Well, like light cavalry throughout history, they're good at the beginning of the battle, finding openings in the opposition formation and perhaps prising it open a little more for exploitation by actual battle winners.
And at the end, when the enemy are scattered and disorganised, light cavalry are the ideal troop choice for preventing them rallying and re-consolidating.
And of course your army needs someone willing to carry the fight to the enemy, someone to go toe to ballet-shoed toe with the opposition.
Landraider might well be the most stylish way to deliver this lot into the fight. Perhaps not the most elegant, but certainly the most stylish.
These jovial minstrels were all painted by Raven's Nest Painting. So there's a modest build up of Eldar forces going on as well.