Towers

Towers give no plunder but they give constant defence. If you have 0 troops and a def tower you will still have a certain defence left because of the tower

 

do u want to lose plunder if u dont care then go ahead but if not id just buy pots

 

It's your choice. A def tower gives 40k defence and a spy def tower gives 20k spy def (those are stats at maxed out level). Just remember that if you get one your attack or spy atk cannot be as high