What is the optimum PC level for Death Frost Doom?

Question

The 2014 edition of Lamentations of the Flame Princess adventure, Death Frost Doom, says that it is "suitable for low level characters". I've read the adventure thoroughly, and am aware that it can be randomly deadly for any level of PCs, but I would like to hear from people who have actually run the adventure as to the optimum PC level for a one shot. I read recommendations for the 2009 edition of levels 3-6.

I want to run the adventure as a one shot, and for it not to be a TPK because of the PCs being too low level, or too easy if they're too high. Again, I know there are many level-independent ways to die.

Answer 1

3rd-6th level should work

You do not have to take it from me. James Edward Raggi IV shares this in his foreword to the 2009 version:

I’ve personally only run this adventure, both in its combined finished form and its original separate parts, for characters 3rd level or less. However, I suspect the main issues will remain challenging through sixth level, and there is one reason: At 7th level, spellcasters gain the ability to speak with plants. While it may be unlikely that players think to use this at its most opportune time, doing so effectively turns this adventure into a mapping expedition in an odd location rather than an adventure where participants will stare death in the eye.

So if you want to avoid TPKs without making it too easy, the top end of his experience should work fine. The adventure is kinda slow, with little combat during most of it, so I think there is no need to go higher than 3.

Note that the original version had a plant creature in location 22 that this intro refers to, while the 2014 edition replaces this with (p. 38) "a combination of parasitic undifferentiated tissue, manifested ectoplasm, unholy ice, and liquid time". So the speak with plants issue is going away.