This goes to an age old question of which one is superior: magic or might. In a contest of sword and shield, Thunder would win hands down. In a contest of dark arts, Maze has the upper hand. It boils down to how well each uses what and how well they can defend against each other's attacks. For me it's just a question of time. The longer the battle, the more it favors Thunder. Maze has that physical shield, making him invulnerable. But he cannot regenerate power while using it and once Thunder beats on him long enough that shield dies and Maze has no power left to fight but physically, and in a melee matchup Thunder will win. He just needs to survive the magic attacks long enough to wear down the shield.
But let's not make this boring. There are other heroes who would object to this duel and or join in the fighting. Jack would want to ensure that his errand runner doesn't get killed over an idiotic comment like "I'd tap Whisper". Briar and her interest in scholarly wizardry and crap would make her partial to Maze as well. Whisper would side with Thunder, unless her lesbian romance with Briar in my slashfic* confuses her decision. >.> Weaver/Guildmaster would be more interested in stopping the fight, and has many abilities at his disposal to deter violence. Who knows if Nostro and Twinblade with their respective armies and any other formidable folks that I'm forgetting (Theresa? No.) might pop in at this very opportune moment to cause some chaos. What am I forgetting... oh and balverines are attacking.
Not boring anymore. But I'd rather not contemplate such a scenario.
*I do not write slashfics. Maybe I should.