HQ- Shas'El, Burst Cannon, Missile Pod, Multitracker 80 pts
Elites- 2 Crisis Suits with Twin-Linked Missile, Flamer 94 pts
Troops - 10 Kroot 70 pts
Troops - 10 Fire Warriors 100 pts
- Devilfish Transport, Disruption Pod 85 pts
Fast Attack - Piranha with Fusion Blaster, Targeting Array 70 pts
Bonus! 2 units of 2 gun drones
This small force is very similar to the army I ran at local 500 pt Tournament. It's mobile, has a good helping of weapons from S5-S8 but lacks long range anti-tank firepower. If you facing Space Marine Predators, you'll have to use your Deathrains, moving up the flanks to hit side armor. Av14 is a concern with only one melta gun on the board so use it wisely.
I haven't tried this list out so I'm sure if it needs any tweaks right now. The basic plan would be to set up a firebase with Kroot set up in front, Fire Warriors behind, near their Devilfish. Drones from the 2 vehicles drop and move to prevent the Kroot from getting into hand to hand, acting as a speed bump unit in other words. Crisis Suits set up to provide anti-transport fire and remain near the Devilfish. At some point the Fire Warriors or Kroot will need to jump in the Fish to make it scoring to claim objectives. The Crisis Suits will link up to escort the transport.
Don't be shy about using pulse rifles on Rhinos. Even at this points level, Space Marines can mech up easily and even the Pulse Rifle can torrent a Rhino to death. Just remember when the enemy gets close to jump back in that Fish.