Alarm building: bell tower
A building that can be an alarm bell that when a unit gets within range of it clan castle troops and heros will be alerted and go to the alarm bell to attack and defend as well as having defences that are not attacking point towards the alarm bell (cannons and stuff aim but don't attack until a unit is in range) this bell tower would be 2x2 and cost 10,000 gold to buy at town hall 7+ take 2 hours to build and like a trap this building would have to be rearmed after it is actived costing 100 gold to rearm and having a range of 3 but upgradable to level 2 for 40,000 gold taking 6 hours to upgrade and increasing the range to 4 and rearm cost to 150 gold and make the bell more golden less rusty and then a final upgrade to level 3 requiring town hall 8+ costing 100,000 gold and taking 1 day increasing the range to 6 and rearm cost to 200 and makes the bell larger (larger in the image not space) this alarm will also have a limit of 1 so you can't place or build any more. The alarm building will also have 500 health/hit points but gains 100 more with each upgrade level 1=500hp level 2=600hp and level 3 =700hp.
this building is called the bell tower and will have a discription saying: when enemies are near the bell tower will alert your defence of attackers.