When the mobs get defeated, there will be either a Horizontal or Vertical lasers that can damage you. If the Skull is on the right side of the mob, it will be a Horizontal Laser. If it is on the top of the mob, it will be a Vertical Laser. Make sure you are not in range of those Lasers when you defeat mobs. The main hazard is Gravity Barriers. There is also Elemental Effectiveness so your Wood monsters will deal more damage and be able to mitigate just as much. Bring Wood NGB monsters to deal with the main hazards.