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I'm in the process of building a Dark Eldar army that is completely converted. After reading the fluff on Harlequins, I thought that it would be a cool idea to incorporate these awesome models into my army. I figured that Wyches were the best unit in the Dark Eldar unit to represent the Harlequins.
Here is the unit entry I've put together. Could those of wider experience tell me if it would work as a Harlequin unit?
Agoniser, Combat drugs, Haywire Grenades, Gruesome Talismans, Mask of the Damned, Spliter pistol, Crucible of Malediction
9 plasma grenades, 2 Haywire grenades, wych weapons, 2 shredders
If you're wanting to use the Harlequins models as Wyches, that sounds like a good idea.
If you're wanting to use Wyches as proxies for Harlequins, well... I guess it could be done...
--•-My 40K projects-•--
I do this myself, I'd say Wyche rules do a very good job at representing Harlequins-- both are virtually unprotected, lightning-fast, elite combat specialists. If I remember correctly, in the old Harelquin Codex, all they had was a 4++ in close-combat, just as Wyches do. Fusion Pistol models can represent models equipped with Blasters in a pinch. One nitpick, the leader of the troupe would be a Great Harlequin, the Solitaire is... well, solitary.