Hmm Urien is a bit weird as his strength buff doesn't really help out wracks that much ... But I would do a battalion ... Here is an example list I thought up (I don't know your area so this is just a general coven list)
++ Battalion Detachment +5CP (Aeldari - Drukhari) [55 PL, 1002pts] ++
+ No Force Org Slot +
Detachment Attribute: Prophets of Flesh
+ HQ +
Haemonculus [5 PL, 70pts]: Haemonculus tools, Splinter Pistol, The Helm of Spite
Urien Rakarth [5 PL, 90pts]: Diabolical Soothsayer, Warlord (Haemonculus)
+ Troops +
Wracks [5 PL, 115pts]
. Acothyst: Haemonculus tools, Liquifier Gun
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. 7x Wracks
Wracks [5 PL, 115pts]
. Acothyst: Haemonculus tools, Liquifier Gun
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. 7x Wracks
Wracks [5 PL, 115pts]
. Acothyst: Haemonculus tools, Liquifier Gun
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. Wrack with special weapon (up to 1 for 5 models): Ossefactor
. 7x Wracks
+ Elites +
Grotesques [6 PL, 105pts]
. Grotesque: Flesh Gauntlet, Monstrous cleaver
. Grotesque: Flesh Gauntlet, Monstrous cleaver
. Grotesque: Flesh Gauntlet, Monstrous cleaver
+ Heavy Support +
Talos [12 PL, 196pts]
. Talos: Chain-Flails, Macro-Scalpel
. . Two Haywire Blasters: 2x Haywire blaster
. Talos: Chain-Flails, Macro-Scalpel
. . Two Haywire Blasters: 2x Haywire blaster
Talos [12 PL, 196pts]
. Talos: Chain-Flails, Macro-Scalpel
. . Two Haywire Blasters: 2x Haywire blaster
. Talos: Chain-Flails, Macro-Scalpel
. . Two Haywire Blasters: 2x Haywire blaster
++ Total: [55 PL, 1002pts] ++
Created with BattleScribe
The idea would be to keep Urien near the talks and grots as wrack cc weapons are "poison" and pushing the grots to strength and toughness 6 and the talks to 7 would let them threaten pretty much everything, the haywire on the talks is both for lowering cost and giving you a bit of anti tank.
The wracks won't have a vehicle but with three grots and 4 taloi I don't expect them to be shot at right away, the two ossefectora per unit should give them a nice way to dish out mortal wounds and the acothyst with a liquifier gun (as hilariously under strength as it is) should help with the unit being charged or just a little extra close range fire power for getting opponents off objectives.
For the artifact I went with helm of spite because it's the only psycher defense we have but you could also go with vexator mask to keep a unit from overwatching.