What I would do is create a map of the actor names, and assign them a number. Create an actortype attribute. Create a number attribute (call it"PoolNumber" as an example). Set PoolNumber to a random integer between 1 and 6 for example. Do an "if", "otherwise if" string of blocks... These will be pools for different odds on generating an actor. So if PoolNumber =< 2, you'll then have another random number decide which actor to pick that has a 1/3 chance of spawning. "otherwise If PoolNumber = 6", pick an actor that has a 1/6th chance of spawning. Just make sure your map has actors of different odds numbered in order or their odds so that the random integer is between x and y in the map. Hope any of that makes sense. Here's sort of an example of something similar I did where my actor names are just numbers (I didnt use a map):