I have no skill for making .avis, so here's the textual mission briefing
for The Odium:

<insert world-weary Garrett-voice here>

Tonight I have something ambitious planned.  I've learned that a religious
cult called "The Order of the Inverted Hammer" has recently acquired some of
the things I... appropriated... in times past.  They've gotten hold of the
Mystic's Soul and Heart gems.  Normally I wouldn't care, but I've been hearing
rumors lately that they're using them to access an item said to be beyond price.

This is plenty of incentive to get me trotting out there.

Their fortress is a place called "The Odium".  It used to be a robber-baron's
keep years ago, and is situated at the top of a pass in the mountains some miles
east of town.  It's a very defensible position, but was abandoned for years before
the Order settled there.  The front gate is very well guarded, but a friend told 
me of another way in - an old steam vent coming out of the machine room.

The Inverted Hammer are nasty guys - necromancers and murderers.  They've been
known to do things that even I won't talk about.  They're led by a man named
Trystich, a man said to be truly evil.  Some speculate that he's a vampire, 
others a demon - but nobody has ever seen him. Breaking into their fortress 
is madness.  But, anything for a buck... I once robbed a god.  But
I never robbed the devil.

<end of Garrett-talk>

The Odium is a fairly difficult level.  The differences between the difficulty
levels are quite minor - basically just how much health you get.  You have to 
steal the two gems and the first hammer, meet your loot quotient, and escape.

There are three ways into the building, and two ways out.  The interior also
has a few secrets of its own.  Oh, and about the sanctuary - going through it
*is* possible.  It's just tricky.  Have fun :).