Oh, I just had one of my usual "crazy thoughts" :
Imagine kind of a rifle. Kind of.
What it shoots are not bullets or anything like that,
but spells encapsulated in a glowing, white or blueish ball.
A bit similar to those balls the Gungans throw in Star wars episode I.
Only that in this case the balls are kind of containers for kind of "compressed magic" - spells contained in them.
What kind of spiells is variable. The rifles could be able to shoot *any* of these containers, because the glowing ball-like containers are separated from their contents. And the rifle is prepared to just shoot the containers, nothing else.
And of course this all needs a capable mage who can put the spells into the containers ... Or even better : Two mages : One creates the ball-like container, the other one directs the magical energy of the spell into it, then the first mage must "close" the container ...
