For Slasher (if you don't want to check the Aleroth link to avoid spoilers) on the second level of the catacombs, about halfway between the entrance and the stairs down to level 3 there are a couple room type areas, one of which contains a tile...
Have you talked to Goemoe since Zandalor told you about the teleporters? The abbey area may be a little tough until you get into the early twenties, or so, for character level.
I went for the second teleporter stone right away. It was a bit of a hectic fight at that level, but having the use of them from the start of the catacombs was very handy.
