Not bad at all. I have a few recommendations:
-Your Archon is too expensive. Drop PGL, you shouldn't get charged anyway, plasma grenades are enough. Spend the points to get an agoniser (see below)
-Trueborn shouldn't be in CC, so they don't need plasma grenades.
-I would go the extra mile and buy an agoniser for the Hekatrix. With the Archon joining them, the unit will have 8 agoniser attacks even without charging and eat any infantry unit alive!
-I would avoid paying for shatterfield missiles. You're going to use it mostly against infantry, and most infantry are T4, so Monoscythes wound very easily anyway.
-Your Trueborn squad will be a massive fire magnet since they don't have a transport. For a footslogging unit, their weapons also don't synergize well-the range difference between the shredders and SCs will either cause you to try to close with the enemy thus leaving cover and getting shot to pieces, or those 4 shredders will just sit around all game and you will have wasted points. Warriors in a dakka Venom are cheaper, more versatile (w/Blaster) and more survivable IMHO.
The Ravager-all jagged metal, guns, and death.