I obtained this crash while flying around in creative mode, after I decided to punch a Crimson Cleric in the face while he was drawing... whatever it is they draw from the eldritch portal things. Initially I thought this was solely a Thaumcraft problem, but with all the Blood Magic references in the crash report I thought it might be prudent to post it here first.

http://hastebin.com/segilasewe.vhdl

EDIT: This is with the very latest Thaumcraft and Blood Magic off of Curseforge.

Simple hit with empty hand on any living entity will cause this issue.

SSP or SMP? I'll fix this when I get back from the movies assuming @TehNut doesn't get to it first.

I was testing out a new modpack in SSP at the time.

I was in SSP aswell.

SSP on mine aswell.

I have the same Issue, but I just hit a sheep in the face with an ImmersiveCraft Saw.

All fixed! This will be available in the -12 build. Thanks a lot for reporting it, guys!