Doomsday Singed!
I know this quick little drawing is terrible but use your imagination (or someone draw up something better!)
He would have a busted turbine on his back that you would see the blade spinning around and smoke/sparks spewing out of the top of it and down. When he ults, the sound of a jet engine would ramp up like it's going to take off (instead of a much calmer idle sort of sound during normal use)
His wrapping around his body could be different colors of wires, some exposed to the bare metal and sparking.
His shoulder plates could be large hunks of plate steel with different bolts/screws/rivets in them.
His skin would be fused together and have implants for the eyes.
The shield could maybe be a piece of a wing or something.
I imagine when he's "activated" he's sort of like a giant walking electromagnet and all these parts and things were partially welded together and partially held there by the magnetic field.
When he dies, he could either take off (jet engine) or just fall apart and explode.
thoughts?
singed, grumpymonkey, etc for vision and great justice!