I was thinking about making the game a little more friendly to newcomers, and I came up with an idea. I know D is already buffed, but I thought about replacing the engineers regular grenade, or giving him a new build-able. My idea was for a proximity alarm. One that gets triggered when the enemy crosses it. It can be destroyed, and the engineer would only get one or two per life. It would consist of a device placed on a surface that broadcast a beam across an opening. See my crude rendering below.
