Should have been the Eureka Effect, hehe. I never liked Lord of the Rings, in fact I despise it, but this is just incredible. However, the hair and beard on Engineer could have been done better. On this it just looks...wrong.
Hm. Took me a moment to get the Lord of the Rings connection. That explains the grey beard and hair on the Engie. But I must admit, I don't like the hair and beard. I think they look ugly. There are some beard miscs in the game now, maybe use those? Or just leave them off. The iconic things I associate with Gandalf (the Grey or the White) are his pointy hat and robes. Why not use the Crone's Dome or the Point and Shoot hat, both are pointy, large-brimmed "wizard" hats.
The Medic would work in this role, too, because he has the long, dramatically flapping labcoat. But I admit, the Engineer calling down lightning into his wrench, Thor-style, works thematically better. But "wrench + lightning" begs for the Eureka Effect wrench to be used!
As for picture composition, can you move the frame a bit more to the right? There's a lot of unused space to the left, while on the right side of the picture and Heavy and Scout are bunched up at the edge and the Heavy is nearly out of frame. Right now, there is a big gaping empty space with only background in the middle of the picture and the eye cannot decide if it should focus on the big hulking robot on the left or the tiny group of characters on the right. Move the two groups onto the thirds in the picture, and let the lightning bridge the gap. Or better yet, try different angles and move the virtual camera to behind the Heavy's left shoulder at a 45 degree angle, so that we see the characters partially from behind, and see the robot looming over them.