Illusions that die by walking into enemy static aura or deafening aura drop nora globes. There may be other passive damage abilities that cause this that I haven't seen. However when vashal mirrorblade spawned illusions under snogvies aura lots of globes appeared. Just saw grimlic deception onto static aura from stormflyer cause the same thing.
Walking alone won't do that. It's spawning within range of such auras that will cause illusions to drop globes as the damage happens before they receive the illusion condition, I believe.
You can also add that if a split-hero's illusion appears in a FF BG or a full hero's in a split BG via illusion of lies, it'll instantly die and drop a globe. @Sokolov I guess it's about the order of abilities proccing? (on-deploy kill and damage from third source effects triggering before the illusion condition applies)