It's happened to me twice now, where I'm near the end of the level and frantically trying to heal when I click slightly outside of the heal spell circle (nowhere near 'restart') and it restarts the level. :( Maybe have a confirmation after clicking restart? (and yes, I'm going to try to use the 1-2-3 shortcut keys for spells now, just to avoid this)
 "Villainous"){kind=icon}
 "Over The Border"){kind=icon}
 "The Linear RPG"){kind=icon}
 "Apokalyx"){kind=icon}
 "The Final Death Wish"){kind=icon}