Creatures with the hanging death animation can not be targeted either, which is why an area effect spell that doesn't need a target is required to force completion.
You could try a different weapon, to see if the frost/stun combination is the problem. If that helps but you do not want to give up frost weapons, you can use
iZakaroN's SaveEditor (or from
Kiya's site, with description) to remove the skill points you put into the passive Stun skill.
The Kaa Gent scroll is a reference to a soccer team.
Catacombs under Warrior's Guild query...There are no treasures under single boulders, though a couple may be partly or fully hiding a key (which hitting the alt key should bring up the description for). If you see a pile of boulders (or crates, etc) then check it out; several piles either contain treasure or block a door/hatch leading to another room.
