Light Rune location
Goto Chapter 3 and a witch and her sister will give you the rune and a spell.
Fire Rune location
Goto Chapter 4 and defeat the Beguiler and his clown to get the rune.
Goto Chapter 8 and reunite the lost brothers to get the rune.
Goto Chapter 10 and reunite the two children with their mother to get the rune.
When close to a mushroom ring, save your game, quit and reload to restore health.
To get a type of magic that can kill anyone just get a red cape and have the strongest fire attack, then press Y, Y, B, Black, White, A, A, X. If you do this right you will hear a loud yell.