Mage Knight: Machination
Spontaneous Blaster
Prerequisites: Technomantic Staff, Spot: 4 ranks, Point Blank Shot, Mage Blast must be one of your known cantrips.
Benefits: You may “lose” a prepared cantrip of 3rd-level or higher in order to cast Mage Blast without preparing it ahead of time.
Normal: A magus must prepare each of his cantrips ahead of time, just like a wizard.