Siege Defense -Vines, Spike Traps and Rocks-
I was thinking it would be a great idea to be able to freebuild defense barriers, or for elves just have them radiate outwards from the walls as you build layers. Each city has its own unique barriers. Can be built anywhere a unit can walk.
Large Rocks: Boulders able to be placed to obstruct enemy movement. The enemy most go around the rocks, or destroy them. If destroyed, they may yield a bounty of stone to be looted. These are effective when holding a position on a bridge and what-not.
Vines: Thorny Vines erupt forwards from the walls, slithering down for a small distance, which can be upgraded buy buying more. Eventually you will have vines that go for a good distance in any direction. Any unit walking on them has its movement slightly impeded and takes a small amount of damage. Can be destroyed by attacking ground with siege equipment.
Spike Traps: Can be freebuilt anywhere where the land is flat. Any unit passing over this trap will be greatly hindered by its speed and take a large amount of damage. Can be destroyed by attacking ground with siege equipment.