Top block breakable to tnt

in most factions servers the top most y level block is invincible on all sides. this is done so that regens need to be broken the more difficult way. currently with the top most y level block being breakable any regen can be destroyed very easily. To fix this there are two options: Option 1: make the top block completely unbreakable by any explosions. Option 2: ban regen walls and increase the amount of power a faction can claim and the amount of walls they can have outside their base. (flat walls/non-regen walls are easier to get through so you want to allow players to have more of them)