There is currently a bug in this monster which sometimes causes it to move in a random fashion: going in circles, running away whenever it's within range, or even following the party for miles. It has been observed to follow all the way back to the Ghostly Hero, for no apparent reason. This can cause many problems, especially if the party does not equip snaring skills or Crippled-causing skills. The boss is an effective healer, and it moves quickly, making it nearly impossible to hit with AoE or sometimes even projectiles. Melee characters will also need to Sprint to keep up sometimes. If this happens and your party does not have any movement-slowing skills, you can watch the circular path of the monster. Before it gets near a barrier such as a wall, a rock, etc., stand in its path and surround. This can be accomplished with henchmen if you simply order them to hold ground at the spot where you want to trap Issani. The creative use of mission-specific Splinter Mines can make up for failing to bring cripple; these are bundle items which impose both cripple and bleeding on members of the opposing team. This bug seems to have appeared as of the October 25th update, which changed the monster AI.