Practically the only visible thing left from the BTNInvulnerable icon is the outline of the shield
and that's the only thing i find wrong on the icon... maybe you could put something around the shield edge (keep the shape; just put a cable-like 3d outline along the edge)
Correct. Under many layers there is a gradient version of Blizzard's BTNInvulnerable and the shape of the black outline is practically from it too. Otherwise it's freehanded with GIMP. I admit that it is a little blurry but I haven't figured out how I could improve it :/. Thx for the comments BrownSnow .