I was about to toss a bucket of lava on a block of obsidian, but in attempting to select the bucket, the game froze and eventually crashed to the desktop. The crash log indicates a Null Pointer error in the ExNihiloOmnia module.

Thread: Client thread
Stacktrace:
at exnihiloomnia.items.ENOBucketHandler.bucketFill(ENOBucketHandler.java:49)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_398_ENOBucketHandler_bucketFill_FillBucketEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
...

I've attached the crash log. I hope that helps in diagnosing the problem.

fml-client-latest.zip

Seems to be similar to the above one:
http://pastebin.com/YNDXMutT