relating to sensation or the physical senses; transmitted or perceived by the senses.
Such senses are: sight, hearing, smell, taste and touch.
Focusing on just these five, here are some examples of harmless sensory effects as I understand it:
Touch: a puff of wind
Hearing: faint musical notes
Smell: odd odor
Taste: a flavour
Sight: such as a shower of sparks
So, what is the difference between this and an illusion? What constitutes as a harmless effect? Is a door considered a harmless effect? Is a raincloud considered one? Can my horse have a rainbow nyan-like cat on its fur? Is the sensation of a hand touching someone considered a harmless effect?
I don't understand the spell, can someone please explain to me what is the meaning of "harmless sensory effect"?