02-16-2018, 02:58 AM
Insects are an interesting group to deal with concerning illusions. If I am correct, as in the case with mantises, they see and react to movement which simplifies their brain processing power. I could see an insect either being exceptionally susceptible to illusions because of their simple mindedness or incredibly difficult to influence for the same reason. Either way the best way to handle them, in my humble opinion, is use an action to deal with illusions the same as other creatures. As long as a creature has a wisdom score it should be receptive to an illusion and it is only fair in game terms. At the core of illusions, proof of disbelief is on the viewer and not the caster, even something completely obnoxious in a given setting would realistically cause a viewer of an illusion to pause for a moment. For example, I know magic illusions aren't real but I am out for a 2 mile jog when all of the sudden I see a psychic tandem war elephant in front of me. I am going to stop and react in some fashion. 
