Perhaps we can allow placement of barbed wire that damages and slows all people who cross through it. It would be a extra secondary item option and would replace grenades when chosen with several units of wire. Placement will be restricted to the tops of blocks and it would take 2-3 seconds or so to place per unit and it could also be broken with a spade at normal block breaking speed or a bit longer thus serving as an effective border making material to slow enemy charges into your territory. This block would hurt all who pass through it making it a dual edged sword (otherwise it'd be overpowered). The block could wear away after it has been passed through several times (similar to trampling it) also removing it.
Thoughts, Opinions?