Such a character would be the thaumaturge's best friend.
Amusingly enough, we don't have a single spellcaster in the party. There's an Ex-Special Forces Sniper (now retired and a Firefighter) whose grandmother taught him to shapeshift -- originally he was just looking for a way to improve his eyesight -- who is relatively nasty in a fight.
Then the Emissary of Morpheus who has been granted great powers... in the dream world.
Next, the 'mortal' cursed with the Sight who sees far more than he actually wants to see...
And finally the Changeling who would be far happier if both Summer and Winter would leave her alone and let her finish her studies as a medical student.
The Emissary and the Sniper are the two with a flair for combat. The Changeling just sits back and racks up the Assessments, Declarations, and Manuvers... It's worked well for them so far.