Haunted Witch Tower and Haunted Island

Hello,

I have an idea about new feature for the game: Haunted Witch Tower

Haunted Witch Tower would look as the usual Witch Tower which can be won from adventures (RB and DB I think). It would provide the usual 100 settlers population. A new feature or the twist to this building would be that it would also contain enemy army.

I suggest it this way:
After being constructed it will glow a bit (to inform that enemies are inside). Player would have to defeat the enemies gathered in the tower - the same way as he/she defeated camps on island before. He would receive some loot for it of course. Enemies in the Haunted Witch Tower would be higher level - as in the RB or DB - but preferably new enemies like Ghost or Banshee or Skeleton etc (as it is "Haunted WT"). After a time, let's say week or two after it's defeated, it will be full of enemies again (so it will glow a bit again) - they would respawn. Each time they respawn they would be different (numbers, species, etc.) but still the higher level ones.

Goal:
Goal and motivation for players to defeat it again and again (except from the fact that it is a new feature) would be that in the loot from this tower would be an adventure never seen before. Adventure called Haunted Island. This would be also high level adventure, and only possibility to get it would be from this tower.

Math behind (chance to get it):
For normal Witch Tower is there 2% chance to get it. Nothing of this would change. Only that there would be a let's say 20% chance (1:5) that the received Witch Tower is actualy a Haunted Witch Tower. Player would find this out after receiving the loot e-mail.
For defeating the HWT there would be a let's say 2-5% chance to get the adventure in the loot. As the tower can be attacked only once a week or two it would take a while to get the adventure.

The reason why I suggest new (unseen) enemies in the tower is because in the adventure would be also enemies from this new cathegory.
There can ne new achievements and/or quests for all this...

What do you think?

Sammy