Today I had a team including Dust Devil and Scorpius.
Scorpius has trait Desert King and thus every brown ally get +1 to all stats. And he does indeed do so.
Dust Devil receives this +1 to all stats but even when he rises to magic level 20 the damage done is still only 5.
Every other troop I put in Dust Devils place until now gives more damage when his magic rises only Dust Devil stays at the same damage. I haven’t tried every brown troop yet but all those I did try had their damage going up along with the magic level.