What we need here is to add a new tower system that will give more motivation to players to evolve and raid.
For example, combine a max level poison tower with a max level bomb tower and u get a mortar tower that casts at a long range poison bombs with a large AoE.
To get at lv.2 mortar tower u need to add a max level firestorm tower, that will give the lv.2 mortar tower higher attack rate. To get a Lv.3 mortar tower u need another max poison tower that will increase the tower’s poison damage, etc. The combination of these towers to make the Lv.2 Lv.3 fusion tower, etc will require blueprints (which u ll get from special INVENTOR events) and additional only MAXED towers. They r not upgraded only with gold like the rest.
fire tower+bomb tower = napalm tower (tower that throws AoE bombs at a high range, which cause blunt damage on impact and then burns for 3 secs with a chance to cause panic)
lightning tower + blockade = electric fence (blockade that stuns and hurts melee units)
OF COURSE to access these fusion structures u ll need to get the blueprints from the INVENTOR events too
If u fuse existing towers with pearl upgrades these pearl upgrades can be transfered to the towers u combined to the resulting fusion tower.
If u upgraded the range of the bomb tower u used by +20%, then the range of the mortar tower would be +20% as well, if the poison tower was blacksmithed to do +300 damage, then the poison bombs of the mortar tower would have +300 dmg. That would be an extra motivation to use blacksmithed towers, of course u ll be also able to blacksmith mortar tower after u build it too, the max blacksmith upgrade could be reached in both ways.
The only problem that should be dealt with, is to able to built towers NOT on your defence path (and thus at the expense of your kingdoms defence) but in a neutral place within your castle. To do that, I suggest that the inventor’s hut will become something like the blacksmith and have slots, only these slots will allow towers to be built at the same time. Of course the construction of a tower in the inventor’s hut slots will require a worker.
Fusion towers will open a brand new AMAZINGLY exciting chapter for RR2 kingdom tower-defence development and FG!!!