Anti Mage Weaponry

Suggested by Burned_Ice:

So. Mages in large scale battles. They got AoE and can explode things with their mind. If I was a general or any kind of tactician I would be very careful to keep my mages at the safest possible place where they can still work their mojo, and I'd set snipers to peg any enemy mages. Or anyone wearing a robe or waving their hands. Really just anyone not in armor.
However mages would hide behind melee walls so its hard for a traditional bow-wielding sniper to do much. So I present anti-mage weapon #1

Spiker-It's pretty much a miniature collapsible ballista on a tripod. A designated soldier carries it on his back. When a battle starts all the soldiers with these scatter and try to take any high ground they can behind the lines. They then set up the Spiker and search for mages. Point and fire. It doesn't have the force or range of a true ballista but it outshoots a crossbow. It's usual ammo is yard-cloth arrows (arrows for longbows). There's a crank on one side to reload since a human would have his arm pop out of the socket before he could pull back the drawstring barehanded. It gets off about 1 shot ever 1.5 minutes

#2 Mana mines- A double-edged sword. These are floating glass spheres enchanted to be attracted to any source of casting, when they reach a certain proximity they explode. Unfortunately using these also shuts down your mages

#3 Meta-mages-You know what they do.