you could set it up through scripting i think like this.
create one enemy like the picture above and place it in a level then create one that has only red eyes and no other texture and place this in a dark room perhaps a black room. right click on both entities and set the spawn at start to no, then place a trigger zone outside the door to each room, type the name of the enemy in the if used section. and change the main script to this (compliments of uman)
;Artificial Intelligence Script
;Header
desc = Umans Zone Activate an Entity on entering zone
;Triggers
:state=0:state=1
:state=1,plrwithinzone=1:activateifused=1
this method will allow for the enemy to be called upon before you go in to the room and it will not be active 100% of the time. this script works on basis of distance. so if you wanted to have one enemy chasing you and then all of a sudden do the "vampire is now in front of you" thing you just set up the triggers to make it happen. also by having an entity with a black texture except for the "red eyes" will allow it to be invisible except for the eyes in a black room.
but remember that if a room has more than one door you will need to place a trigger at each door, or if you want that player to walk through a room with no enemies and then when he has to return the same way he has came he will have to fight the enemy you placed in that room. <--make any sense?
"I am ready to meet my Maker. Whether my Maker is prepared for the great ordeal of meeting me is another matter."
-- Winston Churchill
