How about this one?

Ornak (100)
Brunak (110)
Kee-Mo-Shee (130)
Blade Gruts (40)

TOTAL: 380

A turn with Ornak activating Brunak and Kee, plus 2 more turns of Kee should be devastating. Use the blades to clean up.

For a 500-pt army, add 3 more squads of Blade Gruts, and use a giant horde sweep for cleanup.