Postby Rogan Rubyeye » Sat Jan 04, 2014 1:51 pm
Hmm, interesting question and definately one that's open to GM interpretation. Undead are usually the province of the nethermancer, but if you make them immune to illusions, then you're shafting any illusionists out of most of their abilities. Not even bringing up the whole do illusions work when viewed astrally thing - Earthdawn often differs from my GM's Sixth World-ingrained magical theory.
Overall, I'd say that if the thing's physical then illusions should affect its senses (i.e: indirect illusions - ones that create an effect that the target witnesses via their usual methods of preception). If its got some cognitive capacity/sentience, then directed illusions should also affect it to some degree (i.e: illusions that actually target the creature's mind/consciousness), but these wouldn't affect the brain-dead types - skeletons, for example. Astrally active undead/spirits are a different kettle of fish entirely, especially if they use a different form of sensing than the usual five senses of Name-givers. Sort of like ghosts/wraiths seeing life energy or possibly patterns and magical threads, for example.
"I spy, with my Targeting Eye..."