Bookwyrm627: I just pulled a pretty wicked shield out of a ruin. Of course, this means the local Undead-player wraith that was hiding in the fog hasn't been wiped out, so I'm down to blocking tunnels with units to keep it off my otherwise helpless casters.
ZFR: What does this mean?
You searched a ruin and found an item, right? What does hiding in the fog mean?
I was able to see a ruin that I could raid for an item, and I was able to see a razed city to rebuild in the other direction. I could tell the city was a 3 hex city, but I couldn't see the third hex, so I couldn't see the wraith. I sent units to investigate and loot the item-ruin first, and when I sent someone to scout forward toward the razed city, I didn't have enough movement to kill the wraith.
By "fog" I meant "fog of war"; I assume this phrase is common lingo. In case my assumption is wrong, it comes in two varieties. There's the unexplored hexes (covered in black) and the hexes that are explored but not currently visible (covered in a grey shroud). I don't know if there is a special term for the unexplored terrain, so I just use fog of war for both versions.
ZFR: and blocking tunnels with units? does it simply mean you put units between the wraith and your hero? Wouldn't the wraith simply attack them and reach your hero anyway?
Bingo. Underground tunnels lend themselves to chokepoints, and I filled one of those chokepoints with expendable fighters. The wraith would have to go through my blockers to reach the casters and builders, but the units blocking the chokepoint should
easily destroy it now that they've got Enchanted Weapon to bypass the wraith's physical immunity.
ZFR: There is a razed town with a wraith next to me. And a monster lair.
I take it I must take the town, but I assume the wraith is too strong still?
Wraiths only have 2 def and 6 hp, so they tend to go splat as long as you can actually damage them; the Wraith's trick is that they are immune to most types of damage. You need Magic, Holy, or Lightning damage to hurt them. Enchant Weapon is an easy way to enable melee units to kill them, but most non-Southern maps don't have magic in such abundance that you can enchant all your units pell mell.
They are also vulnerable to Turn Undead and Dominate. A pair of priests should be able to wreck a solo wraith.
Most races should be able to kill a wraith with 2-3 swordsmen with Enchant Weapon, though the Dark Elves and Goblins might need an extra unit because of their lower damage.
ZFR: Are the monsters in in the lair randomized?
That depends on the map maker. I believe the map maker can set specific guards, but otherwise the guards are at least somewhat randomized.