They can be killed by an attacker easily and help them build a huge counter push. Tanks: Pekka, Mega Knight, Giant Skeleton. Put at least one ranged unit and a heavy tank in all your towers. (recommended) buildings are: Tesla, Inferno Tower, Bomb Tower.
Also, put buildings in your central tower because they will always spawn in front of the tower they’re slotted in. Since the elixir refill is really fast in these games, you should keep your defence heavy. So, we will keep this generic so that everyone can use them. Also, instead of just one or two, there plenty of good combinations that work. So, our suggestions are useless if you do not have a card levelled up. It’s really pointless to list specific combinations down for you because the cards are level dependent.