http://paste.cisien.com/f/484fec0b.txt

While this doesn't call out Botania directly, I believe this mod is the source of this crash.

I stopped getting this crash after I removed Botania.

I wish i could give you more detail other than this...
Seed: 1449317119036395715
the crash occurs around -623, 1321

If you can't repro in this seed/this location, then I can bundle up this instance and put it up for download.

This isn't Botania afterall.