New trap - Hidden Wall

So how about this, a hidden wall trap. Like the other traps (bombs, teslas etc) the hidden wall will have a radius and once a troop gets within the radius, it shoots up from the ground. (much like the way a hidden tesla shows itself). The radius of a HW or hidden wall will be an non upgradeable 2.5 tiles. The HW does not take up 'red zone space' like all other traps.

At town hall level 8 the trap becomes available and you get a maximum of 2. At town hall 9 an additional 2 are available and with town hall 10 two more become available to buy giving you a total of 6.

The HW doesnt do damage to an enemy troop but rather, prevents them from crossing. They can be used to divert an attack through a specific place or simply create a barrier. Much like any other wall, the HW can attach to other walls (and also other HWs). HWs are also similar to normal walls in the way that hog riders can jump over them, jump spells can enable other troops to jump over them too and wall breakers can destroy them.

Now, you may be asking, what Hp do these walls have and what do they look like? Well, HWs are upgradable and change in appearance according to their level. HWs upgrade the same as normal walls but at a different price. They require a builder and do not reward xp when upgraded. Their hp are directly proportional to the same level normal wall and in appearance they match the level of normal walls but with a green glow. (eg level 1 are wooden but with green glow) They are obviously unseen by the enemy until they are triggered.

LEVEL COST (in gold)
1. 400
2. 2,000
3. 10,000
4. 20,000
5. 60,000
6. 150,000
7. 400,000
8. 1,000,000
9. 2,000,000
10. 4,000,000
11. 6,000,000

Note that the price is (the price of matching level normal wall x2) apart from levels 10 and 11 where they are (the price of matching level normal wall x1.5)

I think that about covers my idea up it's probably not thought into very well but I didn't see it in other threads so I thought I'd give it a shot. Please give some feedback as it would be greatly appreciated.