dirty, filthy trick of the day:
1) take an allied inquisitor with the books of pain radical wargear. drive him upto the enemy (preferably in a land raider!). the enemy will no doubt try to mug him with everything range in their turn... (careless fools!)
2) your turn, read from your dark texts and pin every unit with a model within 3"!!! now drop all your guard units onto your opponent's opposite flank and watch as his/her army is helpless to support the threatned flank
overall, yes it's pricey! but if you can pull it off there's litterly nothing that can stand upto this trick
(well, except fearless armies obviously...)
cheers!