I do Mechdar at 500, it's pretty fun
78 Farseer Guide, Singing Spear
120 Falcon Pulse Laser, x1 Shurken Cannon
76 3 Guardian Jetbikes x1 Shuriken Cannon
76 3 Guardian Jetbikes x1 Shuriken Cannon
75 Viper Missile Launcher, Shuriken Cannon
75 Viper Missile Launcher, Shuriken Cannon
Could easily swap guide and the spear for Doom, whichever you prefer, he runs in the Falcon.
For the Footdar 500, I would agree with Dr. Serling, something like this to cram lots of good choices.
155 - Avatar
60 - 5 Dire Avengers
85 - 10 Guardians, Shuriken Cannon
100 - Wraithlord with Wraithsword OR Shuriken Cannon - 2 Flamers
100 - Wraithlord with Wraithsword OR Shuriken Cannon - 2 Flamers
I might want to run some warwalkers at this points level, too.
75 - Farseer with Guide, Singing Spear
60 - 5 Dire Avengers
66 - 3 Jetbikes
180 - 3 Scatterlaser Warwalkers
115 - Wraithlord w/Missile Launcher
Something like this has a decent Firebase with a small Avenger Squad to escort the Farseer. Shoot up your opponent with lots of Strength 6? One might prefer to have more resilient Troops, though. I like bringing as many guns to the fight as possible