my guide has some more insightful strategy for the fights, but these are designed to be won with einar's full help:
- second floor, northwest room, einar can make a noxious brew to skip the kobolds fight, if you have >= 7 AGI
- he fills your soup flask in the kitchen in the east wing of the main floor (near to the where you found the potions)
- free bonfire kit bonus at the entrance
if the strategies in the guide aren't enough (which is possible, rng can be cruel, especially with the kobolds), you can quick save and quick load every turn to get favorable rng (attacks you can defend, crits, dodges...), but i did make it with low stats and pre-nerf (without skipping the kobolds, which were rng hell), so it is possible. i admit i did come up with a strategy to stall and fully heal in some cases with the nightstar sachet (dawnstar sachet bought from chet and powered up at the dragon statue) though, so not having that might make things almost impossible if you can't skip the kobolds and have low stats, given you lack potions too (unless you opt for the save-scumming i explained above).