is it not possible to rest in irenicus prison ? after the first rest in the dungeon ? i have 2 skellies left with 1 bar hp and i am trying to rest up to make new skeletons.... but after 30 reloads or so still not able to rest without a enemy encounter..
Make the starting dungeon slightly harder
This is a very low-key modification to the initial dungeon. It replaces the pathetic goblins with duergar (which I think has a better "feel" to it in any case) and it prevents you from sleeping more than once. (I allow you to sleep once because (i) it gives you a chance to choose your spells, and (ii) Imoen has some rest-related dialogue that I don't want to block.)
At 18:30 he's using arrows of detonation to quickly kill the enemy, it's the best tactic. In 2.5 LoB skelis are pretty weak because enemy gets -11 AC so they aren't hitting much, the video is probably core difficulty which is also a lot easier. If you're playing C/M, here's how I dealt it with Trabb: https://forums.beamdog.com/discussion/62202/the-lob-scs-solo-challenge-proudly-presents-the-crusaders-of-blades-and-stars/p124
Mostly precasting Skull Traps, Webs and Cloudkills from the scrolls. Spell Sequencer robe from the Kanaglym lich also helps.