The Multiple Spell is a type of Null Magic allowed the user to multiply the amount of times the same spell which he/she cast.
Episode 3- It was used against the dullahan to cast the [Shining Javelin] spell.
Episode 6- It was used in conjunction with [Enchant] to paralyze the bandits surrounding the Mismede bound party.
Episode 6- It was used to cast [Shining Javelin] to power the magnifying glass Touya made with [Modeling] to burn a hole in the dragon attacking them.
Episode 9- It was used in conjunction with [Program] to heal the wounded soldiers of the Kawagoe Fortress.
Episode 9- It was used against the hundreds of invading Takeda forces to cast the [Shining Javelin] spell from the sky.