Sandbags and landmines. Pretty self explainitroy sandbags you place them for quick cover in the open would be very useful in flat maps like Iceland and would need to be destroyable with guns but strong enough so people shoot the person behind it when they peek and not just break their cover (could make is so a single grenade could break them to balance it easily. Landmines basically c4 but u don't have to trigger it (No really?) either have an anti personal or antitank (prob antitank because anti personal wouldn't go to well) and definitely don't make it both anti personal and anti tank so c4 is flexible but hasto be triggered. (U can shoot it to disable it pretty simple unless your not paying attention and then you go boom.)