Ok, so I am doing another attempt at a Frozen Crown Solo using @Wodjee's run as a template. YouTube video can be found here - https://www.youtube.com/watch?v=miTjrBLDaQ4. On my first attempt all went well until I got to the part where I need to rescue Giacco (refer to 17:50 in the video). I entered the cell southeast of Giacco, pulled the first skeleton and then had him walk back to his post without him discovering me. Of course, once he walked back I tried to pull him back in by approaching him. Net results was that I aggro'ed both as I was badly out of position and that of course pulls all the undead and lead to a quick death. Ok, so attempt number two and roughly twenty minutes later, I pulled the skeleton, had him walk back to his post and tried to unstealth before he was out of sight and again aggro'ed both and died shortly thereafter.
Luckily I realised at this point, that it might be a good idea to do a special character allowing me to test the mechanic. Unstealthing when the skeleton reached the point where he stops tended to give me a roughly 50% chance of just pulling one. Of course, after getting a couple of decent results with the test char, I did the same thing again with a new FCS Rogue. He ended up dying again about 20 minutes into the run due to facing too many undead in that tiny cell...
Luckily the 4th time was the charm and I managed to only pull one. At this point, they got what they deserved!
So, after this lengthy post, does anyone have any advice for what I could do to ensure that I get this correct 100% of the time for my next run?