"So, to summarise the background of the conflict - this is the provincial army of the province of Stirland, under the command of Elector-Count Ableheim Van Hal, and the area we're in is the Haunted Hills area on the border of Sylvania with Stirland. Sylvania fell to corruption when their counts married into vampire bloodlines and have been a blight on the face of the empire for hundreds of years since.
The current campaign's goals are primarily to destroy as many minor to medium sized monsters and problems - things like the Blasphemy of Blood, while we have the military, diplomatic, and economic slack to do so, to ensure that when the next real war occurs whichever necromancer is running the other side can't drag all of these things up to supplement their army. Secondary objective is to build a road to enable further campaigns through these hills. A complete purge isn't realistic; the terrain is to too broken. Even if we achieved a total victory and killed every necromancer in the region forever, the land is so poisoned and there are so many little hidden caves, that even in five hundred years time there will still be ghouls and skeletons popping up.
How undead work - obviously the exact details are classified, but the broad strokes of fighting them aren't. Many of the undead we'll be fighting are spontaneous and self-motivated products of the corruption of the land but intentionally created undead can often be killed by disrupting the formation they were raised in sufficently, or by killing the guiding necromancer. Many undead, especially vampires, can regenerate - though not forever, unless they're Vlad Von Carstein. If you do kill a vampire, keep track of the remains, though, and hand them off to a specialist for storage. A necromancer actively maintaining an army can repair and reanimate the fallen of both sides in real time - all the more reason for someone like you to focus on taking out the head. Some undead are quite venemous, yes - ghouls in particular. If they're ambiguously alive and unambiguously ravenous, that's probably a ghoul. Vampire and Necromancers often know dangerous magic, including spells intended to slay instantly - sometimes even on the scale of entire regiments. I doubt that we'll face anyone of that callibre in this campaign, but you can never be sure. Specters and banshees are also capable of striking through most mundane defences, and the latter have a killing scream as well. The only ranged attackers they will have are whatever local militia with shortbows or crossbows they've managed to press-gang, and precious few of those - even the most powerful necromancers often don't want to bother with the logistics burden of peasent archers in an army with otherwise perfect morale and no hunger or exhaustion. Instead, you should be wary of flying monsters - swarms of giant bats and vargeists are likely the worst we will see, but terrorgeists and reanimated dragons are not in principle impossible.
Terrain-wise, these hills are some of the most broken and innavigable hills I've ever seen, and if we get through them, then on the other side is a nice wide stretch of cursed swamp and blighted forest, and on the other side of *that* is the thin strip of whatever excuse for farmland the Sylvanians have managed to maintain in the face of the levels of dark magic they have to deal with, and then somewhere on the other side of that is the World's Edge Mountains into which the Zufbar dwarves are dug. Hopefully, they'll be able to send us reinforcements, but they're busy dealing with some underground war of their own for now, against beastmen of some sort.
Timing wise, this campaign was set to be three months but it's looking like it will drag out to longer. Less than a year, though, if it takes that long we'll have to pack up and go home."