In my current Clash of the Titans campaign one of the characters picked up a mutation that allowed his character to smell magic. I ended using the following table to simulate this:
Magic Generally – Ozone.
- Evocation – Coriander.
- Conjuration – Black pepper.
- Transmutation – Earthy smell.
- Abjuration – Freshly Baked Bread
- Divinition – Chocolate.
- Enchantment – Orange.
- Illusion – Cherry.
- Necromancy – Cinnamon.