Karandras
5 Striking Scorpions including Exarch with Scorpions Claw, Crushing Blow and Stalker
This comes at about 400pts, although you can choose to add a Dakka Serpent (I personally don't due to the assault limitations), and is a tough unit to crack in combat. It relies on your opponent not having knowledge of how potent Karandras and his Scorpions really are or forgetting about them for more pressing concerns.
It starts by infiltrating the unit about 12" - 15" away from the enemy, out of Line of Sight.
At the first opportunity you charge this unit into the enemy, making sure Karandras and as many Scorpions are in base contact as possible, to ensure maximum mandiblaster damage.
Then accept any challenges with the Exarch, but do not declare any of your own, and pray to the dice gods that you hit with enough attacks to cut the unit down to about 3/4 models, but not wipe out the unit.
Safely sit out the opponents shooting in combat and laugh as your opponent rushes troops to the meatgrinder/ tarpit, away from the rest of your army.
Rinse and repeat.
For even more added goodness, get the Avatar as close as possible, to attract fire and, if he survives, sweep in and destroy a unit.
Also try adding more Scorpions and watch the panic in your opponents face.
So what does everyone think?
Any Striking Scorpion tactics of your own?