Hi there
I'll be gentle ...
1. You need to drop some wargear from this list and up the count of bodies on the field, or you will run out of soldiers pretty fast.
2. I always advocate the dropping of bio-explosives and expensive pistols, as my Harlequins should always be FoFing down the field anyway.
Bearing this in mind this is what I think.
2xShadow Seer 140pts 287pts
+2xShuriken pistol 2pts
+2x Bio-explosive ammunition 10pts
+River blades to other one 15pts
+Harlequin's Kiss to other one 10pts
+2x D-field 50pts
+2x Dread mask 60pts
The masks I think can go. As well as the bioexplosives. The rest is pretty cool I think.
3xDeath Jester 141pts 257pts
+2x Fire pike 36pts
+Missle launcher to the third one 15pts
+2x Rictus mask to those who have fire pikes 50pts
+Phase field to the one with the Missle launcher 15pts
oouch ouch! The DeathJesters should stay far back and out of trouble. Give them long range firepower and let them bust tnkas and dreads for you instead. Brightlances gives you the ability to move and fire, and you can drop the rictus masks and phase field. This also frees up a lot of points.
5xMimes 125pts 168pts
+2x Harlequin's Kisses 10pts
+Mimic 12pts
+Shuriken pistol to the Mimic 1pts
+Bio-explosive ammunition to the Mimic 5pts
+Powerblades to the Mimic 15pts
Nice. Pricey but nice.
10xHarlequin troupe 250pts 304pts
+2xHarlequin's Kisses 10pts
+2x Fusion pistol 16pts
+Troupe leader 12pts
+Shuriken pistol to the Troupe leader 1pts
+Bio-explosive ammunition to the Troupe leader 5pts
+Harlequin's Kisses 10pts
Drop the pistols and the leader, and unless you are fighting Nids you should consider getting a powerweapon and a kiss in the squad instead of 2xkiss.
The leader ties up a lot of points that you need to beef up your numbers. Scaling groups of Harlequins into six will allow them to be transported along with a Shadowseer into the thick of battle, where they can be supported later.
10xHarlequin troupe 250pts 311pts
+2xPower weapon 12pts
+2x Fusion pistol 16pts
+Troupe leader 12pts
+Shuriken pistol to the Troupe leader 1pts
+Bio-explosive ammunition 5pts
+Powerblades 15pts
Same as above.
2xVenom 90pts 170pts
+2xShuriken cannon 40pts
+2xHolo-field 40pts
These should get holofields and fusionguns, and they will not be quite as useless, and somewhat more resilient. Move them in cover at best speed until you can unload the Harlequins on them, and then set them tankhunting.