Tower specific items ( "aghanim's scepter")
Just a quick thought:
An item like aghanim's scepter in DotA which amplifies a heroes ultimate ability.
something like this would be quite interesting
like a bag of carrot which increases the number of attacks if baby rabbit is equipped woth it
or an antenna which increases the range of electric chair and so on
this could also be a fragmented card set discussed in another thread with the resulting card being tower specific
#1 the new card will grant part of the abilities of the crafting tower to the tower equipped or
2# only grants a new effect to the creator
either way we could make the unique/legendary versions really strong since it would be harder to craft
+ 1 for me as well, I'm always for a Special item that would unlock a special skill/trait for each tower (or a set that the tower consumes or has to wear for it as well)