Don't think your 'normal mage' is someone, who as stated by Zorbak, was only one of 3 possible people who could have broken Drakkonnan's force field (Zorbak, Warlic and Cysero) were the three
As @dragon_monster already pointed out, Cysero stated himself that the solution was a sponge soaked in nitroglycerin. That's not magic; that's science. Hence it falls under the category of him knowing
a lot of obscure things
~original: @dark garuda
And for most of his powerful actions, they're represented by him as being not much of an effort at all on his part. Or they're taken for the benefit of something trivial (because he doesn't really have any priorities). That would suggest that his actual potential power, if he needed to use it, would be even higher.
Well, it would logically follow that someone so uncaring would be unaffected by the results of whatever it is they don't care about. However, Cysero is not swayed by logic, and not caring about things that directly affect you is, well, insane behaviour.
and you very much forgot a MAJOR requirement to be called a "deus ex machina". it has to be a COMPLETELY NEW or UNRELATED developement to the story.
According to that requirement, the 'deus ex baconia' was not even a deus ex machina, since the Bacon Orb was set up before the finale; it had its own questchain.
As far as I recall, the most powerful magic Cysero has done is merge a cat with a book. His creations are strange, but that's mainly to do with their design, not any measure of raw power.
Mostly, Cysero's main skill is paying attention to obscure things.
And he possesses the most important skill; knowing when to run, as with the time booth.
< Message edited by Shiny_Underpants -- 5/15/2017 4:03:26 >