Playing as the weakest kid on the playground makes the frail Mage a tricky class to start with. The fact that his early spells are nearly useless is only bested by the fact that he can't cast many of them. Getting picked last for the kickball team is old hat for the Mage - he's a weakling: the worst in close-range combat and wears no armor to speak of.
Luckily for the Mage, striking the killing blow counts for skill points just as much as fighting and winning a pitched battle. Capturing control flags also gave us rookie spell-hurlers much-needed early levels. Mages can choose the path of fire or lightning based spells, and even at the middle of our career arcs, we eventually started laying down some heavy artillery.
Mages rain down fireballs that have a huge splash damage radius; at higher levels they even learn how to steer them. Perhaps the most fun we had was trading fireballs with other Mages - to great effect. We also loved luring folks out into the open by casting a seemingly harmless 'ball straight up and out of sight. This was extremely effective thanks to Dark Messiah's advanced graphics - looking into the sun is momentarily blinding. Once they emerged, we'd steer it back earthward again, slamming into them from out of nowhere. Evil, evil fun.
At high levels the Mage can be nearly godlike, able to cast increasingly powerful attacks fueled by manna upgrades that allow them to sling heavy-duty spells virutally without pause. Mages also gain the ability to cast a magic shield around themselves or other teammates, making them an essential, you'd-better-not-pick-them-last member of the team.