Now I do not know if there are more informations about the strange obelisk on the Asmodian side, but visually Bollvig's Obelisk looks the same as every other Asmodian Obelisk. I also did not include the hero killing Bollvig here either, because it seems to hold no big story change for now and he apparently re-appears in 3.0 (I do not know if it is only as a side boss or as someone who actually influences some part of the story or land.)