Oh no, it's the SUPER wizards. They just sat and watched before - while all of their comrades were slaughtered - but now they are here to single handedly defeat the 100,000 strong army.
It is a bit foolish, I'll admit, but they may also have been super careful about when to employ them.
When there exists monsters that can disable all skills, which would likely include spells, something wizards rely on to a fault, it is prudent to be sparing with their deployment.
So to prevent them from being sniped, it is reasonable to avoid situations where they are able to be sniped. Besides, if the enemy has something capable of disabling magic casting, then they would've likely deployed them in order to slaughter their mage garrison, that they haven't means it's most likely they lack such capability, thus, deploying the super mages now means they simply have to overpower whatever is shifting the tide.