Sarloveze told us that Iron Leg is hella painful to use at first. Out of the magics, I think being attacked with either acid or sand would be the most painful.
Why sand? Well because with enough strength, sand can eat into your skin and slowly wither it away. It can get into your eyes, blind you but it just get stuck in there, you can’t get it out all that fast. Sure, you can close your eyes, but is it any help when you’re in battle? What about when the sand starts eating through your eyelids? Your actual eyeballs???