axewarrior20
((Yes I am a noob, but with military experience(games and such) so I know half and half of what I am saying, lol.))
as I tried to post earlier before the taco database consumed my previous post of this...
As a Witch Hunters player you've got quite a few choices to make before proceeding. You need to choose whether you want the Sisters, inducted guard, or allied space marines (although fortunately there isn't anything stopping you from having the sisters with guard).
Anyway, the sisters have some interesting options. I don't suggest expecting each squad of them to be able to both deal with tanks and infantry. The Exorcist is what you want to use for tankbusting, although penitent engines and sisters repentia aren't too bad at it.
Acts of faith will save your a**. I watched an entire Blood Angels army dissolve under boltgun fire with one act of faith in effect. Since then the acts have been toned down a little, but they're still enough to save your rump.
Officio Assassinorum agents don't win games by themselves. The Callidus and Eversor have a tie for most popular, followed closely by the Vindicare. Nobody seems to use the Culexus much anymore.
Orbital strikes are your friend. Trust me on this one. BTW, there's no limit on how big a terrain piece you have to choose, or where on the terrain piece the template goes- one of the FAQ author suggests targeting "large stuff- like board spanning rivers and such."