U Mad, bro?
HQ
Overlord w/ Mindshackle Scarabs - 105
4x Tremorstave Crypteks w/Seismic Crumble - 130
Troops
10x Warriors - 130
10x Warriors - 130
10x Tesla Immortals - 170
Elites
C'Tan w/ Writhing Worldscape and Lord of Fire - 230
10x Deathmarks - 190
Fast Attack
10x Scarabs - 150
Total - 1235
OR
Heavy Support
Annihilation Barge - 90
(Plus Res Orb and Tesseract Labyrinth for Overlord)
Total - 1250
So, Place each Cryptek with a different Troops unit, and the Cryptek with Seismic with the Deathmarks, and the Overlord with the Immortals. The troops are there to form a general gunline and take objectives, and the Crypteks slow down anything he hits with Difficult Terrain tests. Meanwhile, the C'Tan will sit back and make said Difficult Terrain Dangerous Terrain instead. The Cryptek with the Seismic is with the Deathmarks to (maybe) ensure they will have at least one turn to move away from any units assaulting. Depending on whether I'm facing vehicles or troops, the Scarabs race ahead and om nom on vehicles, or the Barge will take advantage of the enemy troops bogged down.
This is just a list I thought up. I doubt it would be competitive, but I figured it will still be a fun list to play around with. Suggestions to better tailor it would be most welcome.