personally these are the changes i'd make to your list.
1. give the archon an agoniser so he's able to do something with your grots.
2. drop the scourges and get another 5 man warrior squad in a venom in there.
3. reavers, unit of 6 with cluster caltrops. I find reavers to be more versatile than scourges but you could just keep the scourges and drop the jetbikes. get another warrior squad in there somehow basically.
4. drop the lone Talos for a third ravager. i love talos but i would field at least two or do the dark artisan formation. you'll get more out of a third ravager than one Talos IMO.
having lots of variety in units is nice and looks great but personally id rather have multiples of just a couple choices otherwise you get that jack of all trades master of none thing going on. example being your Talos. its not really doing much but drawing fire. okay cool but you only got two ravagers. so say your opponent ignores your talos and takes out a much more vital ravager. you now only got one. that limits your primary anti vehicle units by 50% and your talos is still just sitting there. thats why i'd go for three ravagers.
the same with your fast attack choices. drop one and double up on something else (or as i suggested add a fourth warrior squad). keep your razorwing incase you want some anti air plus you get extra lances (cant get enough). scourge vs reavers is a personal choice. like i mentioned i like reavers because they can assist in assault with your grots, move around and capture objectives, tie up troublesome units with hit and run, and hurt vehicles. scourges, well they can hurt vehicles and capture objectives, thats about it. not saying they're bad at what they do but it just depends on what you want.
i cant comment on eldar allies because i dont use them. looks like a standard option to take, wave serpents are great.
your list may look something like this
Archon (Agoniser, WWP, Armor of Misery, HWG)
4 Grotesques in Raider (DL)
5 Warriors in Venom (2 SC)
5 Warriors in Venom (2 SC)
5 Warriors in Venom (2 SC)
5 Warriors in Venom (2 SC)
Razorwing (2 DL)
6x Reavers (2 CC)
Ravager (3 DL)
Ravager (3 DL)
Ravager (3 DL)
Spiritseer
5 Dire Avengers in Wave Serpent
5 Dire Avengers in Wave Serpent
good luck with your tournament! hope this helps some