The buggers, I have prided myself on how good I have become on the DoW games and when I got to the Sisters home base level, I got my arse absolutely spanked, not once but twice!!! - Bitches
Just defeated them, although their stronghold was strength 16 I didn't find it too bad because of the way the mission is setup. You spawn in the bottom corner of the map, so basically they can only attack from the North. There's a heavy cover crater just to the northwest of your base, so I filled that with:
-1 Veteran Scout squad (2 sniper rifles +Apothecary)
-2 Veteran Space marines (both with heavy bolters +apoc)
-1 full Space marine squad (Sergeant, 3x HB, 1x Missile Launcher, +Apoc)
-My commander (Hero upgrade, Aura, doomhammer, meltagun, ~6000h, boosts to regen and speed, reduced melee/ranged damage etc).
Basically what would happen is, the enemy approached and my commander would charge in and engage in close combat to halt their advance, meanwhile they are getting scythed down by all that fire power. With 4 Apothecaries present I could pretty much leave that unit entrenched in heavy cover to defend my base (along with 2 veteran assault marines and 2 land speeder tempests +static defences to the northeast) while I attacked with my main force (2x Terminator, Grey knights, 2x librarian, chaplain, 2x predator annihilator, 3x dreadnaught, 2x assault marines, 1x space marines).
Only problem really was destroying a couple of the shrines due to them being invincible when the Saint is close, so I had to split my force and made use of landspeeder tempests to attack undefended shrines.
Funnily enough just like Dark Crusade I think the Orks were maybe the toughest enemy I've faced so far due to numbers and the Squiggoths.
Just got one race left to defeat now, Strength 17 Imperial Guard. I'm guessing I may have some trouble if they use a lot of vehicles as I tend to find my base vulnerable to them.
The good news is I've got a big Deep Strike force queued up ready plus my 6 Honor Guard units so I will hit the ground running!