I thought of this idea a short time ago, so it may not be all that viable. However, it would be hilarious should it be pulled off correctly.
My idea is this: Ally with an army that will allow you to use the Blind special rule (the only one I could think of off the top of my head is CSM), and use it against a tough unit to crack, like the unit the enemy's warlord is in. Assuming their fail their initiative check, that unit will now be WS1 and BS1.
That's when Lelith charges in.
She has 4 attacks base, 1 for an extra CCW, 1 for charging, and a whopping 8 for her special rule concerning the difference in WS (don't have the codex in front of me so I don't have the name) for a whopping 14 attacks that all ignore armor! Even at S3, there's still enough attacks to take down most units or HQ models.
The look on your opponent's face when you pull this off would be absolutely priceless.
Bonus points if you use a unit of Hellions with a stunclaw to drag their precious (and expensive IC) away from his bubble-wrap before dropping the bomb.
I realize this will be tricky to pull off, but will get you style points from onlookers (and will make a great battle report) and will cause much wailing and gnashing of teeth from your opponent.