Negative Energy Cone

The creature's central eye emits an invisible, magical 150foot cone of negative energy. At the start of each of its turns, the creature decides which way the cone faces and whether the cone is active. Any target in that area can't regain hit points. Any humanoid that dies there becomes a zombie under the creature’s command. The dead humanoid retains its place in the initiative order and animates at the start of its next turn, provided that its body hasn't been completely destroyed. (Death Tyrant, pp. 29, MM)