Cloudkill (Arcana) [Air]
Level: Mage 5, Destruction 5, Air 5, Assassin 5
Fortitude partial. Mana: 10. Base Success: 75%.
  Creates a cloud of poisonous gas that kills outright any creature of CR 2 or less, kills any creature of CR 3 to CR 5 on a failed saving throw, and inflicts 1d4 toxic damage per caster level on everything else (Fortitude for half). Only creatures who breathe are affected. The caster is immune.