Mod Version: 3.5.4.3

Forge Version: 14.23.5.2768

Link to crash log (if applicable):
crash-2019-06-14_20.43.47-client.txt

Description: When playing in a homemade kitchen-sink pack, game would crash at what seemed to be random intervals.
Later found out it was crashing because the sun was in view.
This quickly degraded to the point of crashing whenever the in-game sun was anywhere on screen (even when walls, roof, or ground was obscuring it).
Hope this helps.

This isn't a Dynamic Surroundings issue. It is an issue with the Regeneration mod. Looking at the callstack there is something on a Bibliocraft armor stand that Regeneration does not like.