We need to use shells like some form of explosive. Thats kinda boring so i was thinking to add missiles. It will be part of movecraft plugin. Block requirement will be 100 blocks - 200 blocks with 75% of concrete, 10% tnt and range of 1k blocks. The destruction radius will decide how mutch is there TNT.
How will it work?
Well you place sing LaunchMissile in 1. row and in 2. row will be Name and in 3. row will be coordinates where will it hit. If the coordinates in town thats not under siege, it will give error message: "This coordinate is located in non-sieged town!"
When its launched it will go up (like real missile) and then once 120 blocks higher than launch position it will go straight / diagonal. 50 blocks before the coordinates it will start going down. Missile will not be seen in /craftreport. If 120 blocks higher than position is higher than world limit it will go 10 blocks under it. Add some nice sound to it :D.
Fuel
For fuel it will use lava buckets stored in furnace. For every lava bucket it will pass 800 blocks or less.