This adventure is an interesting start to a storyline set in Icewind Dale, it has a lot of potential for tension and suspense with the constant shadow of a large creature stalking the group.

The reason I give this 3 stars is the following:

• The side-kicks feel very underwhelming, they have a full stat block and interesting back story but no race/name which is hidden at the end of the document with a small paragraph stating you need to prep this beforehand. Not only this, the sidekicks are picked off extremely fast, the characters will barely ever get to use them and it feels railroaded. My characters all tried to grab the expert before his untimely demise because they predicted it was going to happen. Fortunately the rolls allowed him to meet that end as planned.
• The snow birds encounter is pretty useless. I decided to just give them the information with passive nature because they had no idea what was going on and just attacked as would be the natural response. If you have a "strong" group it also suggests using the giant wasp which is a very silly choice as they have a poison effect which 1. Makes no sense unless you flavour it somehow and 2. Can easily insta-kill a level 1 player. They also have less health than owls so that's not great not great in that respect I would recommend increasing the health of the owls to 33 if you have a strong group.
• The 2 caves where the adventurers find the painted stones felt very unnecessary, the map was very small with only the stones inside each. My advice on these is to run these scenerios theatre of the mind as the maps are so small and featureless it doesn't do much for the session.
• The pit of sacrifice has some intriguing depictions and what sounds like a great mechanic but there is just no use I could find for it. I don't see how an adventurer would end up falling into it. I personally added some tension to this area by revealing a fresco to each of the players as they took turns crossing the bridge.
• The final encounter is somewhat lackluster even when using legendary actions and the largest stat block. I really wanted the ability to grab adventurers and use the previous points mechanics by throwing someone in but that would mean sacrificing a multi-attack, I think a grapple would have been a great legendary action instead of shove.

This is all constructive feedback and over all I think the adventure was a good start.