need help for battle coming up

I'm going to play within in he next week and I need to know what to get next, I'm playing against tyranids, imperial guards and tau (one of them will be my ally) it's a 900pts battle.

I already have:

-10 kabalite warrirors
splinter cannon
sybarite w/agoniser

-5 scourges
dark lance
haywire blaster

-Urien Rakarth

Razorwing Jetfighter
monoscythe missiles
splinter cannon

-5 wracks
liquifier gun
Acothyst w/hexrifle

This should make around 700 pts which leaves 200 points for stuff

Thx for feedback

My immediate thought is - buy some transports.
A Venom for the Wracks and a Raider for the Warriors would be helpful. Drop the Wracks to 4 and pack Urien in there. Or maybe two Raiders and don't drop a Wrack.

Also, as a general concept, if you want to run Urien, then you should probably be fielding more Coven units to take proper advantage of his special rules. I frankly think Urien is pretty 'meh' unless you specifically want to run his uber Grots, but even if you're not doing that, he is certainly of more help to the army if there are other Coven units for him to lob tokens at.

I agree the purchase of a raider or venom will not be regretted.
Personally I would add 1x ravager with 3 dark lances
1x raider with dark lance to go with wracks
Extra Wracks to fill out points
I would give the scourges either 2 dark lances or 2 haywire blasters

Dark Eldar are a transport based army and highly dependant on their transports by design. Not having any raiders or venoms is like playing with one hand behind your back. The most common mistake of players new to dark eldar is not to invest in any transports (or very few), and it never ends well.